連日の残業で、もう何かをする気力が残っていない。
After working overtime day after day, I have no energy left to do anything.
彼は最後まで気力を振り絞ってゴールまで走った。
He summoned up every ounce of willpower and ran all the way to the finish.
病気で気力が衰えてしまった祖父を家族が励ました。
The family encouraged their grandfather, whose spirit had been weakened by illness.