Will or volition: one's determination or resolve to do something; the mental force behind decisions and actions.
彼は強い意志でリハビリを続けた。
He continued rehabilitation with strong determination.
意志の力で目標を達成したい。
I want to achieve my goals through willpower.
本人の意志を尊重して進めるべきだ。
We should proceed respecting the person's own wishes.