It depends on whether one is interested to learn and practice yoga for self-inquiry and self-realization to transcend the modification of the mind, to know thyself, or, one is only interested to learn and practice some sorts of physical yoga asana, breathing and relaxation exercises, or, one is interested in both physical and mental practices.
Just as some 'yoga teachers' of certain lineages emphasize on teaching the physical movements and exercises, as they believe that most minds are not ready or suitable for the mental practices before purifying and disciplining the physical body first (perfecting the body first, then only perfecting the mind), and some 'yoga teachers' of certain lineages emphasize on teaching the mental practices (looking after the 'head', and everything else will look after themselves naturally if the 'head' is perfect), while some 'yoga teachers' of certain lineages emphasize on teaching both at the same time, believing that both practices being practiced together are complimenting each other respectively (a knife needs to have both the handle and the blade to be useful and efficient). And there's nothing wrong as they all have their own good reason.
It's about the different degrees of ignorance and egoism that determining which method is more suitable or less suitable for some.
No matter what is/are the reason(s) that ignited the interest to be learning and practicing yoga, either for self-inquiry and self-realization, or to be doing some yoga asana, breathing and relaxation exercises for maintaining and enhancing physical and mental health and fitness, there are some mental practices that are important even before the start of doing some sorts of physical movements and exercises mainly for health and fitness, for attaining maximum benefits and minimizing the risk of injury, not to say, before the start of the intense mental purification process that leads towards self-inquiry and self-realization.
One might not be able to perform certain kind of physical movements and exercises due to some physical condition or time and space limitation, but one can still be practicing yoga if one knows and is engaging oneself in the mental practices in every moment, regardless of whether one is engaging in some sorts of physical movements and exercises, or not, and regardless of what is the physical health and fitness condition, ability and disability.
One can be doing some sorts of yoga physical movements and exercises diligently and regularly, which is also part of the yoga practices that can be influencing the state of the mind to certain extend, which is also impermanent, but one might not be practicing yoga at all, if one doesn't know and doesn't integrate these mental practices into the physical practices, that eventually leads the perceptive mind to go beyond or transcending the impermanent conditions of the body and states of the mind.
There's nothing wrong if someone is not interested in disciplining the egoistic behavior pattern of the mind for self-inquiry and self-realization, to free the mind from ignorance and egoism, but only interested in gaining momentary benefits and satisfaction from doing some physical movements and exercises regularly, regardless of it's from doing some physical yoga asana, breathing and relaxation exercises or some other forms of physical fitness training. It's just that the mind might still be functioning under the egoistic behavior pattern, being over-powered by the passionate desire of craving and aversion, attachment, identification and expectation, and is still being determined and disturbed very much by the selfless impermanent perception of names and forms being perceived through the senses, of sights, sounds, smells, tastes, sensations, and thoughts/feelings/emotions/past memories/future anticipations, that the impure mind spontaneously likes and dislikes, agrees and disagrees with, desires and doesn't desire. And hence, the mind is still restless, even after many years of doing some sorts of physical movements and exercises, while enjoying the momentary benefits and pleasant sensations and feelings deriving from the physical training. These minds would blame others' imperfection and the perceived names and forms that they dislike, disagree with and don't desire, for their own mind reaction of dissatisfaction, disappointment, hurts, painful sorrow, unhappiness or suffering towards undesirable, disagreeable and unpleasant experiences.
A healthy, strong and flexible physical body that can perform many physical actions and movements doesn't and cannot determine a person as a 'yogi'.
Meanwhile, those who are interested in learning and practicing both physical and mental practices at the same time, would be developing essential mental/inner stamina, strength and flexibility that is essential for self-inquiry and self-realization when they integrate the mental practices into the physical practices under the correct understanding and attitude towards the goal of learning and practicing yoga.
One learns about how to observe the behavior pattern of one's mind, to know what is going on in the mind, during the learning process and while performing the yoga practices under certain names and forms. Understanding that those physical movements and exercises as well as the side-effects/benefits deriving from the physical practices don't determine anything, but only serve as tools to help influencing the state of the mind, to help eliminate egoism and quieting the restless modification of the mind, preparing the mind for self-inquiry and self-realization. Understanding that peace, compassion, and the ability to let go, are not being determined by physical condition, ability and limitation. One learns about focusing on one's practice, developing self-reliance through correct understanding and self-inquiry, knowing that the one and only teacher cum practitioner is none other but the mind itself. None can purify and discipline the mind, and remove ignorance from the mind, but the mind itself.
These basic mental practices are indeed the foundation as well as the entire mind purification process of freeing the mind from egoism and ignorance, which is the root cause of restlessness, peacelessness, unhappiness, painful sorrow, or suffering. Upon the annihilation of egoism and ignorance, the mind is free from all these corruptions, where unconditional peace is there as it is, that is uncontaminated, undetermined or undisturbed by the selfless mind perception of names and forms, that is free from identification, or the idea of 'I', 'my' and 'mine'. These mental practices being integrated into the physical practices also help to minimize the risk of physical injury, while allowing the body to absorb the benefits/effects of the yoga asana, breathing and relaxation exercises more efficiently.
It's understandable that many minds are not interested in the mental practices, as it is not a pleasant or agreeable process, and it could be extremely disgusting and painful for the passionate egoistic minds under the influence of ignorance being conditioned strongly by certain worldly thinking and belief. Especially the passionate minds that have strong egoism, or the closed minds that are not opened for anything that is different from their own particular thinking and belief, or the minds that take pride in their 'intelligence', 'education', 'accumulated knowledge', 'origin', 'social status', 'religious status', 'nationality', 'ethnicity', 'achievement', 'profession' and 'life experiences', as well as the disturbed minds that are highly sensitive and defensive, might generate certain degrees of aversion towards the mental practices that meant to be 'weakening', 'breaking' and 'eliminating' the ego, or what the mind thinks and believes, and identifies as 'I'.
And hence, some minds might not be ready or suitable to be practicing such mental practices unless they have certain degrees of awareness, and are willingly to go beyond the aversion/resistance in them, while letting go the ego and egoism that made them think and believe that 'that' is who and what they are, and starting to take responsibility for investigating and knowing what is happening in their own mind, without self-blaming or blaming others for all kinds of corruptions or actions and reactions arising and passing away in the selfless modification of the mind.
1.) Let go past desirable and undesirable/pleasant and unpleasant experiences. Let go future anticipation/imagination/expectation. There's only the present moment, it's impermanent, and there's no 'I'.
2.) Let go any expectation towards oneself, the teacher, the experience, the process, the performance, the practice, the result of practice, the life existence, the relationships, the surrounding environment and the world to be or not to be in certain way.
3.) Let go judgment towards oneself and others, the physical condition/ability and limitation, the mental state/ability and limitation, the teacher, the teachings, the different practices, the consequences of the different practices, and all kinds of names and forms that the mind perceives through the senses.
4.) Let go comparison between one's past and present experiences/abilities/disabilities, between oneself and others, between others and others, between the different types of names and forms (such as between apple and orange), and between the different qualities of the similar type of names and forms (such as between different varieties of apple).
5.) Let go desire of craving and aversion. Allow the perceived reality being what it is, as it is, as it changes from moment to moment. Respect the law of nature and all the impermanent changes as they are. One can still be aware of what is agreeable and disagreeable, but without generate craving/clinging towards what is agreeable and without generate aversion/hatred towards what is disagreeable.
6.) Let go all kinds of identification towards the body and the mind, the existing worldly egoistic thinking and belief, the momentary worldly relationships with all kinds of living beings and objects, the actions and fruit of actions. Observe what is happening in the physical body, what is going on in the mind, and what is happening in the surrounding environment or in the world, without attachment, identification, desire of craving and aversion, judgment, comparison and expectation.
7.) Respect the body and mind, and their ability and limitation in the present moment as it is, even if it's unlikable, disagreeable or undesirable to the impure mind under certain worldly standard and expectation, without forcing the body and mind to go beyond its limitation in the present moment.
8.) Just do one's best, regardless of whether in one's daily life, or in one's yoga practice, according to the present condition of the body and state of the mind, as well as the possibility and impossibility being conditioned by the current situation and the surrounding environment, while allowing the fruit of the practice or the action being what it is. Both possibility and impossibility in the present moment will change. Focus on the possibility and let go the impossibility in the present moment, without attachment, identification or expectation.
9.) Let go the existing worldly thinking, belief and values in one's mind. Allow the mind to be opened towards what is already known, yet to be known and unknown to the mind.
10.) Let go blind-agreeing/disagreeing, blind-believing/disbelieving, blind-following, blind-practicing and blind-propagating. Investigate and inquire the truth of everything, of what is known and unknown to the mind, upon coming in contact with all kinds of names and forms, including the teachings and practices of yoga.
11.) Let go the idea of 'I', 'my', and 'mine'.
12.) Let go the sense of origin, belonging, self-worth, self-image, self-esteem, meaningfulness, superiority/inferiority, and etc.
13.) Let go worldly habits of socializing, gossiping, criticizing, condemning, slandering, back-biting, boasting, glorifying, story telling, scheming, plotting, hoarding, day-dreaming, building castle in the air, aspiring, inspiring, or chasing after attention, acknowledgement, love, liking, support, accreditation, praise, compliment, approval, acceptance, agreement, appreciation, connection, interaction and companionship.
14.) Let go discrimination and interference towards the different qualities of names and forms. Embrace accommodation and non-interference. This is living in peace and harmony with all kinds of living beings of different qualities sharing this space of the universe, both known and unknown, near and distance, without the need of building or maintaining worldly personal relationship or friendship. This is nothing to do with selfishness or unfriendliness, but in fact, it's non-discriminating friendliness towards all and everyone, beyond interactive personal relationship or friendship building. One can be kind towards others and helping one another even when one is disagreeable with the others, and without the need of knowing one another personally. What others do and don't do, what others think and believe or don't think and disbelieve, how others live their life, how others act and react, and what others want to do with their body and mind and life existence, is their freedom. Just mind about one's mind, and let others mind about their minds. It's not selfish. It's compassion.
15.) Let go mental and emotional dependence, passion and lust. Embrace mental and emotional independence, dispassion, renunciation, silence, seclusion and solitude. One can still be performing actions (both action and inaction) that benefit oneself and/or others, that contribute to peace in oneself and in the world, while being dispassionate and renouncing worldly affairs and activities, in silence, seclusion and solitude. This is not easy for many egoistic minds, as most people growing up being 'trained' to be mentally and emotionally dependent on 'parents', 'siblings', 'children', 'family and friends', 'community', 'pets', 'anything that represent interaction of acceptance, love and support', and so on, deeply believing that it's wrong, abnormal, selfish and crazy, if human beings are mentally and emotionally independent, where somebody doesn't need to depend on receiving acceptance, love and support from any other living beings to feel good and meaningful about oneself or life existence.
16.) Develop self-management or self-discipline. Choosing and filtering inputs and activities of the body and mind, unless the mind is no longer being determined, influenced or affected by the physical condition, the state of the mind, and any kinds of physical and mental inputs and activities, regardless of depression or stimulation to the mind. Such as one isn't being determined or affected by food consumption, caffeine intake, sleeping pattern/hour/duration, other people's state of the mind, behavior, action and reaction, the surrounding environment, the worldly affairs and conditions, the personal and group relationships, or certain physical and mental activities. This is not discrimination, but it's compassion towards oneself, knowing that oneself doesn't have strong foundation of non-attachment yet, and would easily be influenced and affected by the different qualities of names and forms, either physically or mentally, or both.
17.) Allow the body and mind to take their own time to be relaxed, to release tension, to build up physical and mental skill, stamina, strength and flexibility, to take rest, to recover, to work, to realize, to understand, and to absorb the effects of the practice.
18.) One doesn't need to be perfect, or good enough. One doesn't need to be a hero to save the world from badness. One just do one's best of what is possible and within one's capability in the present moment. What is good or not good enough, and what is goodness or badness, is impermanent. It's not 'I'.
19.) One doesn't need to be super strong or strong enough physically, mentally or emotionally to forbear pain, hurt or unpleasantness up to certain degrees. One just needs to know the truth of names and forms, or knows thyself, or knows what is going on in the mind, to be aware of all kinds of pleasant and unpleasant, desirable and undesirable experiences, without attachment and identification, without being determined or disturbed by the perceived reality that is impermanent and it's not 'I'.
20.) One doesn't need to be able to know everything, or be able to do everything, or be somebody of certain qualities, or be able to achieve anything, or be superhuman with extraordinary ability, or be positive and optimistic, but just needs to be understanding towards and respecting the law of nature, of cause and effect, of selflessness and impermanence. It's okay if the mind is still under the influence of ignorance and egoism, and still perceiving painful sorrow, unhappiness, hurts, dissatisfaction, disappointment, fear, anger, or any forms of suffering. Accepting the mind as it is even though it's not perfect and still doesn't understand many things, or still be determined and disturbed by names and forms, or still can't let go, or still can't do certain things after trying many times. There's nothing wrong with emotion, to laugh or to cry, either with or without reason, but without attachment, identification or judgment. It's impermanent, and it's not 'I'.
The mind that knows this, doesn't attach onto any names and forms, or be able to let go if there's presence of attachment. This mind is fearless. This mind is void of painful sorrow, even though the body is subject to limitation, uncertainty, unpleasantness, pain, illness, injury, weakness, old age, decay, or cease functioning/decomposition/death.