When you think about whether or not you want to work an hour of overtime, the right way to think about it is, well, i'm already working forty hours. I should say, what's the cost of thatextra hour of what will i be missing out on that i would have liked to do in that hour? And then i would weigh that against the marginal benefit of what i get from one extra hour of work. So by working that extra hour, i'll get some other favors in t future.