Sometimes we mistake what we cannot do with what we do not want to do.
For example, we might say we do not want to jump in the water or dance or give that presentation in front of the whole team, while what we actually mean is we do not (yet) know how to do that. Or perhaps we feel unsure about our skills. It is not a matter of “do not want”.
Other times, we mistake what we do not want to do with what we cannot do
For example, if somebody offers a new responsibility, we might say we cannot take it as we are too busy, but certainly that is not the full story. We are most likely not very interested in the responsibility offered, or we do not want it because it might expose some of our weaknesses. In any case, it is not a matter of “cannot”.
“Do not want” and “cannot” are often used interchangeably, but they are well distinct.
“Do not want” expresses will, power, decision, acceptance. It is a brave decision, and a necessary one in many cases.
“Cannot” expresses an opportunity, incompleteness, desire, potential. It is a step on a long road, and you will get there eventually.
Using them for what they are enables our clarity and helps us focus on what matters (and of course, drop what does not). Do it with intention.