I teach yoga in open classes to mixed ability students, and I also teach 2 classes a week at a disability rehabilitation centre. In these classes, my students have a range of physical disabilities that include wheelchair users, degenerative conditions, and blind/visually impaired people.
Obviously, what I can teach in an open class with people who generally have good mobility is vastly different. But the same intention I try apply to all of my teaching, with all of my students. And that is:
What is the essence of the pose?
So let's use Tree Pose for example (Vrksasana).
In an open class, peoples ability to "execute" this pose can differ. Some people find it easy to stand on one leg, but others struggle with their balance. As I teach, I often see students trying to get into the deepest expression of a pose, often at the expense of their stability/alignment.
So I encourage them to think about the "essence" of this posture - which is to be stable and rooted, but also flexible - if you resist any wobbles, you are more likely to fall.
To do this you need to ground, but also to lift, elongating torso, relaxing shoulders, finding broadness in the collar bones. All of this comes *before* trying to lift the arms overhead, or get the foot higher up the leg.
The supporting leg is the "trunk"; crown of the head, or finger tips if arms are raised, are the "branches" searching for the sun.
This is the essence of the posture.
I also teach a modified version of this to my students that have disabilities. We practice this seated. We start by becoming grounded, then we lift one foot away from the floor. We connect with all our rooting techniques, then hands come to prayer at heart centre, then maybe we lift one arm or both (depending on what movement they have available). They may be sitting down, but it's still a Tree pose!
I like to apply this idea of finding the essence of each asana during my teaching, but also my own practice. It's easy to get carried away, and want to move into the deepest expression of a pose...this is where the ego normally starts to appear :) There is often a yearning to "nail" it, which is effectively a projecting into the future, rather than being fully present in the moment.
If we are compromising our awareness of the essence, pull it back - a low steady tree is better than a high wobbly one!
Whatever you do just keep (or start!) practicing. My experience of teaching people with disabilities has taught me that that yoga is for all. Some of us may have physical limitations, some severe, but there is often a version of something that can be done. Even if it just sitting consciously, and taking a big, deep breath. Yoga is always there, within us. We just need to remember it.