Two questions that cross your mind when you think about doing something:
“Can I do that?”
“Do I need to do it?”
When we say, “I can’t,” it’s only partially a matter of ability. It’s also a matter of need, sometimes even more so.
If you don’t need something, it’s hard to muster the motivation to do it.
If you need something bad enough, you can become capable of doing it.
For example, Maslow explains how the need of hunger turns a man into a hunger-gratifying machine in his “Theory of Human Motivation:”
“All capacities are put into the service of hunger-satisfaction, and the organization of these capacities is almost entirely determined by the one purpose of satisfying hunger. The receptors and effectors, the intelligence, memory, habits, all may now be defined simply as hunger-gratifying tools. Capacities that are not useful for this purpose lie dormant, or are pushed into the background. The urge to write poetry, the desire to acquire an automobile, the interest in American history, the desire for a new pair of shoes are, in the extreme case, forgotten or become of secondary importance. For the man who is extremely and dangerously hungry, no other interests exist but food. He dreams food, he remembers food, he thinks about food, he emotes only about food, he perceives only food and he wants only food.”
Source: A.H. Maslow, A Theory of Human Motivation.