I am amazed when people say “I can’t do this.”
When trying something new, just give it your best shot – then you have given it your all and you did your best. You did not fail.
If you feel you CAN’T do something, to me it means you DON”T want to do something, because your best is all that is asked. Let others decide that they don’t want you to accomplish your best in the future, but it is up to them to decide that.
So give everything your best shot and no matter what the outcome is, it is your best and you have succeeded. If your best is not the desired output for others, that is fine – accept it and move on. Their best may not be desirable for you either.
Be honest with yourself and others – either you will give everything your best and succeed every time, or you really didn’t want to try it at all.