I mean, it's things like that that make me feel the farthest from the nasty oh-bother-why-am-I-doing this dread that crops up every now and then. I think dan put it pretty well:
Grad school is not a means. Grad school is an end unto itself. I am here because I believe it is more fun than anything else I could be doing.
Of course it's not fun and games 24-7, but today was immensely satisfying. Made progress on things, gave a talk that didn't go too badly, had crazy-technical-discussion-over-food with adam and kaustuv. Now... I think I'm going to go buy another toothbrush and do laundry.