We know the benefits of exercise [1] include improvement in mood, but it can also extend to helping ease and prevent symptoms of depression [2] and anxiety [3]. Even though working out is likely the last thing you'd want to do, a little physical activity can actually make all the difference. According to Kirk Erickson [4], PhD, a psychology professor at the University of Pittsburgh, evidence shows "that exercise directly impacts the production of molecules that are involved in mood regulation but exercise also affects many other molecules in the body (e.g., inflammation) that might also impact how you feel."
When you work out, your brain releases feel-good chemicals called endorphins, which interact with receptors in the brain to reduce your perception of pain. Endorphins can also activate positive feelings similar to how drugs like morphine trigger opiate receptors. That's why some people report feeling energized from a "runner's high" after an intense workout. Mayo Clinic [5] adds that exercise can also serve as a healthy distraction from "the cycle of negative thoughts that feed depression and anxiety."
However, the direct correlation between physical activity and mental health are still unknown. All we know so far is that regular exercise can help improve sleep [7], reduce stress, and ward feelings off depression and anxiety. How remains a question.
In terms of how many times a week of exercise is found to be most effective, a minimum of 30 minutes of activity for three to five days a week "may significantly improve depression or anxiety symptoms," according to Mayo Clinic [8], while smaller chunks have also shown to have an impact. Ten to 15 minutes of exercise may even make a difference, especially if it's a more strenuous activity like running. Erickson added that although there isn't a magic number, the general thought at the moment is that it doesn't take much to notice positive results.
The key to enjoying the benefits of exercise largely depends on whether or not you stick with it long term. However, if you have severe depression or anxiety, forcing yourself to exercise when you don't want to might backfire. "When people try to push themselves at a level that makes them feel bad, then they might be less likely to continue to exercise," Erickson told POPSUGAR. "We recommend low and slow — start easy, then slowly pick up the pace over a period of time that you feel comfortable with. Exercise is a powerful medicine."