lol about that one of my uni friends took a yoga class this year, and his teacher said, before going to bed, think of 3 positive things that happened today.
lol i must say lately it was more "soon we'll be on holidays", "ok, only one more exam", "only one more tutorial to work". but surprisingly it helps.
i also gorge myself of tea, usually that calms me down and makes me think more positively.