Paul Waldman says that successfully running for president "requires putting part of your natural humanity aside":
The ability to sustain a particular kind of upbeat mood all the time on the trail can be a function of sheer will, or it can be a function of monomania. Either way, the trail reveals whether the candidates have it. A presidential campaign is a brutal slog. Try to imagine that for the next year and a half, you almost never got a day off (and that means you work weekends, too), you had to meet thousands of people and give hundreds of speeches, and everywhere you went, even when you were just talking to one or two people on a street corner, someone was videotaping you, with your every word being recorded. Also, people felt perfectly free to come up to you and tell you what a jerk they think you are. And you had to smile and act like you like it.
The Dish 