Throughout the entire journey of mind purification and self-inquiry, there will be doubt and imperfect understanding for sure due to certain degrees of ignorance and impurities is still present and clouding the modification of the mind, but both the ignorance/impurities and doubt/imperfect understanding will become less and less as the mind keeps practicing, keeps purifying and keeps inquiring towards the truth of everything, under an open mind free from the influence of any particular worldly passionate egoistic thinking and belief to inquire the truth of everything as it is, even though the ignorance and impurities are not being completely annihilated from the perceptive cognitive intellectual thinking faculty yet.
There's nothing wrong at all, if there are still certain imperfect understanding are not completely cleared from ignorance, that there's still doubt on certain things or certain teachings, until the complete annihilation of the veil of ignorance takes place upon self-realization.
That's why the importance of patience, determination and perseverance that keep the mind going on the path of self-inquiry, on top of non-attachment, non-judgment and non-expectation towards the practice and the fruit of practice. Right effort is also an important element.
Under the intense yearning for liberation, dispassion, certain degrees of right discrimination or basic correct understanding, the basic skill for mind purification, right effort, self-discipline and self-inquiry, as well as patience, determination and perseverance, all doubts will vanish, everything will become clear as it is, eventually.
The limitation in speaking, hearing, comprehending, reading, expressing or writing in certain language, the presence of doubt and imperfect understanding due to the veil of ignorance and impurities in the thinking faculty, the limitation of certain physical condition and ability/disability, the presence of certain difficulty in life, as well as the total amount of chaos, selfishness and corruption in the world of ignorance and egoism, cannot hinder the mind from performing all the yoga and meditation practice that will lead the mind towards self-realization, unless the mind stops at the attainment and maintenance of the momentary physical and mental health and fitness benefits arising from the regular physical and mental yoga practice, enjoying and loving the yoga practice, which is nothing wrong too. It's the freedom of everyone for what they desire and don't desire.
Even though one might be performing some kind of yoga practice regularly, enjoying and loving the many momentary physical and mental effects and enhancements deriving from the regular practice, and/or has been passionately teaching yoga classes to others for many years by emphasizing on the attainment and maintenance of the momentary physical and mental effects and enhancements of the yoga practice, however, if without the awareness towards eliminating the idea of 'I' and egoism, where the mind ignorantly and continuously indulging in the passionate egoistic attachment, identification, desire of craving and aversion, judgment and expectation towards the yoga and meditation practice and the momentary effects of the yoga and meditation practice, that give rise to the false sense of 'satisfaction', 'contentment', 'meaningfulness' and 'spiritual achievement', which stands as a 'cheeky' hindrance that even the mind isn't aware of, hindering the mind from reaching the aim of yoga.
Beware of the ideas and identifications in the mind, such as "I am a yogi," "I am an experienced advanced yogi," "I am a yoga teacher," "I am a qualified and experienced yoga teacher," "I am enlightened," "I am selfless," "I am wise and compassionate," "I am a modern stylish yogi," "I am strong," "I am beautiful," "I am positive," "I am powerful," "I am passionate," "I am deserving," "I am worthy," "I am enough," "I can do and achieve anything," "I am a superhuman," "I can defy gravity and decay," "I am a good yoga teacher," "I am an accredited and well-informed yoga teacher," "I am more than qualified to teach yoga," "I am a famous celebrity yoga teacher," "I am a healer," "I am an inspirational influencer," "I aspire to inspire," "I am the best yoga teacher that gives the best and highest quality yoga classes," and so on, unless the mind is not interested towards self-realization, as life is good the way that one desires in the present moment because one has been sincerely working hard to be achieving and sustaining a life that one desires. There's nothing wrong with that.
Being hardworking and consistent exerting most of one's attention and effort onto performing the yoga practice regularly for many years under the passionate love and intense enthusiasm towards yoga and the impermanent effects of the yoga practice without the elimination of ignorance and egoism will still be benefiting the body and mind to an extend, however, that is not the right effort in yoga.
Unattached towards and go beyond the momentary pleasurable and agreeable effect of the yoga practice of certain impermanent physical and mental health and fitness benefits, if possible, and keep moving towards the aim of yoga, if the mind has intense yearning for liberation, even when life appears to be all good and enjoyable. That is right effort on the path of yoga.
Similarly, teaching yoga classes to others under intense passionate love and enthusiasm towards the yoga practice and the benefits of the yoga practice without guiding the students on eliminating the ignorance and egoism, while empowering the similar passionate love and enthusiasm in the students towards the yoga practice and the benefits of the yoga practice also will be benefiting the yoga practitioners to a certain extend. However, it would be better, if the yoga classes are guiding the yoga practitioners towards the liberation from ignorance and egoism, towards the attainment of self-realization, the aim of yoga.
The impermanent good condition of the strong physical body, the impermanent positive and pleasant state of the mind, and the enhanced physical and mental condition and ability that need to be maintained and sustained regularly, is not the aim of yoga, and it doesn't free the mind from ignorance and egoism.
Living with pure organic products, promoting loving kindness and eating only pure organic vegetarian food from the beginning of life or for many years, also doesn't remove the ignorance and egoism in the mind.
May all be free.