Life is often compared to a marathon, but I think it is more like being a sprinter; long stretches of hard work punctuated by brief moments in which we are given the opportunity to perform at our best.
When you're acting and you need to cry, you want to put yourself in a position where you're trying not to cry, because that is generally what people try and do. They try to hold on to their emotions, they don't want to lose them.