Can't, Won't, Impossible
When young, my daughter often repeated the positive refrain, “Nothing is impossible.” To which I would reply, “You cannot hold a piece of the Sun in your pocket. You cannot look directly at the back of your head. You cannot feel the tip of your right index finger with the tip of your right index finger.” Some things are, in fact, impossible.
When it comes to physical activities, we often wrestle with, ‘I can’t’. A sense of doubt that can become a self-fulfilling prophecy. If you tell yourself you can’t, you won’t be able to, but that does not mean you are not capable. Certainly, some people can accomplish the task with great proficiency. Many can accomplish the task adequately. Many more cannot do it well, but they can do it better than the first time they tried. Sadly, most do not even do that – try.
That said, sometimes there are physical requirements within a martial art or any other physical activity that are indeed impossible for some individuals. It is not possible for a person, paralyzed from the waist down, to run. Age, weight, injury, deformity, deterioration, or other factors may make some physical requirements impossible.
However, that should not dissuade a person from attempting the activity as a whole. Because it is impossible to do a specific range of movements does not mean there will not be accomplishments in other aspects of the overall activity. It is certainly possible to learn hand techniques from a chair, or footwork, balance and body control without arms. I, personally, have grappled with, and lost to, a totally blind man. While you may argue grappling is all about feel, he still had to learn it without ever seeing it. He had to try, rather than saying he couldn’t.
This also holds true for things you are capable of, but find difficult to do. There are benefits waiting to be achieved in the attempt.
The key is to be true to yourself, and upfront with your instructor. A good instructor will test your limits, and find workarounds considering your capabilities. If you have a limitation, acknowledge it and work with it. Do not allow it to become an excuse to say, “I can’t”, when you have not even tried to determine what is possible. The goal is to become a better you, not the best that has ever been.