It's common for people to feel a bit depressed from time to time.
Research shows that people prone to depression feel better when they exercise on a regular basis.
It's quite simple. Our bodies affect our minds. Some researchers speculate that exercise may give people a sense of control, of mastering their bodies. Others say that a moderate increase in aerobic capacity generates a significant antidepressant effect. Granted, I'm not saying a brisk walk is the answer to serious or prolonged depression.