◎ 力不从心 lìbùcóngxīn

[ability falling short of one's wishes;ability not equal to one's ambition;lack the ability to do what one would like to do; the spirit indeed is willing, but the flesh is weak] 心里想做,但能力达不到

今使者大兵未能得出,如诸国力不从心,东西南北自在也。——《后汉书·西域传》