Happiness is…

…knowing that your research is going somewhere,
especially after working 15/7 for the past month.

…being able to squeeze in a jog/workout at 6am or 11pm.

…having something to look forward to: Taiwan trip, someone visiting, upcoming concerts.

…reading interesting books like Dixit and Nalebuff on my way to work, and catching up with blogs on the way back.

…having someone to talk to when I need a break from work.

PS: I’d probably be equally happy working nine to five and use the extra time for more movies, reading, and hobbies. Working long hours raise the marginal return for these activities.