Caffeine should be a good place to start, take your favorite blend of coffee, cola, red bull or green tea if you're into teaine (my favorite is gunpowder [http://en.wikipedia.org/wiki/Gunpowder_tea]). What also really helps is a long shower in which you alternate warm water with icecold water. Start and end with warm water if you haven't done this before. Doing some sports might also help: basketball, squash, ... Or play some action games, for instance the free and freely available Quake Live should get you some thrills.