You can find wonderful fitness facilities at most colleges and universities. As a student, you can use these facilities for free simply by enrolling. Some will allow you to use the gym even if your only taking one class. In fact, that class could be an exercise class, weight training class, swim lessons, etc., to have access to the gym.
Even a few 30-minute sessions a week can bring positive results, both physical and mental. Light weight training, for example, can help ward off the possibility of osteoporosis later in life.