Headstand is the first basic pose in the traditional Hatha Yoga asana practice.
One doesn't need to be super strong and flexible to perform headstand.
What allowing one to come into the headstand is both the body and mind is able to be relaxed when coming up into the headstand, while holding the headstand, and while coming down from the headstand, without tension, judgement, comparison and expectation.
What hinders people to come into the headstand and holding it, is fear. The fear of falling, fear of injury, fear of pain, fear of death and fear of the unknown.
Headstand is an effective asana to stimulate and purify the crown energy centre and rendering the mind calm and quiet for meditation, as well as giving many other physical and mental health benefits, if it is being performed with the correct understanding and technique, and without the interference of the egoism.
Although it is a great asana for many people, there are some people are not suitable to practice headstand due to certain physical limitations and health complications. People who don't have those physical limitations like neck injuries and had performed heart surgery before, and don't have health issues like serious high or low blood pressure, heart problems, eyes diseases, nose and ears infection, intense nose-blocked or headache, or have been advised by their doctor that they are not suitable to practice headstand for some reasons, but if they have great fear of performing the headstand (fear of falling and injuries), then they also are not suitable or ready to practice headstand yet, until they know how to deal with fear, and not being over-powered by fear. If they have great tension in the body and mind due to intense fear while learning to come into the headstand, it will only bring them more harms than benefits. Otherwise, anyone can practice headstand by learning how to come up into the headstand in a gentle and relaxed manner, and keep practicing until one can stay in the headstand for a prolonged period of time, comfortably. But one doesn't need to be able to perform headstand in order to be peaceful and compassionate. It's okay if people can't perform headstand, or any of the yoga asana poses, due to certain physical restrictions.
Falling, whether during the yoga asana practice, or in life (whether physically, mentally or emotionally), is not something bad or negative. It's neither good nor bad, neither positive nor negative. It's part of the learning process to allow the mind to be more open and wise. When one learns how to perform the challenging asana poses under a calm and fearless mind, one would be able to remain calm and stress-free when performing any challenging tasks in life under any conditions and situations.
Just like when we learn how to stand up and walk when we were toddlers, falling was merely part of the learning process. But, we continued to learn how to stand up and walk, again and again, no matter how many times we fell. And gradually, we developed the stability and learned how to stand up and walk without falling.
As parents, they do their best to guide and assist the children until they are able to stand and walk by themselves, in their own pace, without being pushy, without judgment, comparison and expectation. This includes allowing them to fall during the learning process before they develop the stability. The children also continue to learn how to stand and walk, again and again, no matter how many times they fall. The parents allow the children to take responsibility for their action and the consequences of their action.
This is the same as when come to teaching, guiding and assisting the yoga students to come into the headstand.
The yoga teacher should have no fear to teach the headstand to the students, and without fear about allowing the students to learn how to fall in a relaxed manner, bringing the risk of physical injury to the minimum. And allowing the students to take responsibility for their action and the consequences of their action. The teacher must endowed with patience and compassion to guide the students coming into the headstand, in their own pace, without being pushy, without judgment, comparison and expectation. Meanwhile, the students should learn how to confront the fear and overcome it, while developing acceptance, adjustment, adaptation, accommodation, patience, perseverance, forbearance, non-attachment, non-identification, non-judgment, non-comparison, non-expectation, self-awareness, self-control, self-discipline and be free from craving and aversion, during the process of learning and performing the yoga asana poses.
Sometimes, some of the students see other people fall down from the headstand, they might generate fear and worry in themselves towards the headstand practice, even though the people who had fell didn't hurt themselves, and they didn't allow the fall to stop them from continuing their practice. One must learn not to be affected by one's past experience of falling or other people's falling from the asana poses, and do not let fear and worry to stop oneself from continuing to perform one's own practice.
Fearlessness is part of selflessness. The one who has fear towards something, is the ego. Yoga is the realization of selflessness - the annihilation of the ego. The practice of headstand is confronting fear and be free from fear. The health benefits derive from the headstand practice are just some side-effects. Practicing headstand against the wall might bring health benefits to the practitioner, but it doesn't allow the practitioner to confront fear and conquer it, instead, it is running away from dealing with fear.
Whether one can perform the yoga asana poses, or not, it's really not important at all. Even after many times of practice, one might still unable to perform some or many of the yoga asana poses and might fall from time to time, and it's fine, just keep practicing. What matter is, the practice of letting go of the egoism and not being over-powered by fear. Do our best, perform all our duties and responsibilities, without attachment towards our action and the result of our action, allowing the result to be what it is.
If the students have great fear of performing headstand and refuse to take responsibility for themselves, then they are not ready yet to practice headstand.