You might've seen this last night when it began to go viral, but just in case, here's the video of the president addressing his Chicago campaign volunteers. The whole thing is wonderful, but the waterworks begin around 3:30.
I have no idea what he's thinking, but perhaps all of the recent displays of emotion are indicative of the fact that he feels like he's really, really done it this time. He's not just a one-election fluke. He's an historic two-term president who's achieved something very few others have, and he's done so on a wave of millions of people who worked tirelessly to protect the social justice and basic human rights he stands for.