To survive in politics

You have to know this stuff or politics will break your heart (and it may anyway):

I don’t have advice for Prime Minister Brown, I will tell you that you’re always more popular before you’re actually in charge of things (laughter) and then, and once you’re responsible, then you’re gonna make some people unhappy, and that’s just the nature of politics and, these things go in cycles. Even during the course of this campaign, there have been months where I’m a genius and there are months when I am an idiot, at least if you read the newspapers. It seems like I’m pretty much the same guy throughout this process but, you know, my actions and the results are gonna be perceived differently at any given time.

(Emphasis added.)

Obama knows he's not going to be the second coming.