Since they can't turn around and leave, they have to harden their hearts to get themselves through the work at hand. It is only afterwards that they discover the mental toll.
很多人都是一頭衝進去之後，才發現現場怎麼是這樣？可是又不能出來，只能硬著頭皮去經歷這一切，事後才發現它對心理造成的壓力。