Take up running. Pick up a new sport. Start weight lifting. I decided that I'd start running and doing pushups on a regular basis during my past semester and it made me feel a lot better. Granted, I've always hated running, but I'm starting to want to run, and I'm no where near "good" or "devoted" but I'm getting to do something new and different when I go out. It's great to get out some aggression by just thinking through it while your feet move you. It helps you think, too b/c your blood is circulating faster and more often, so your brain is getting more oxygen. Maybe you'll come across something really cool like underwater basketweaving as a new hobby. Not everything costs money, and exercising outside is one of the best inexpensive ways to do something w/o money.
