It increases endorphin levels - Any form of physical activity has the potential to increase neurotransmitters called endorphins in your body. These neurotransmitters specifically make your brain “feel good.” Although this feeling is most associated with running, it can also work for any sort of aerobic activity like playing tennis for example.
It is a form of movement meditation - As discussed in the movement meditation page, exercise is a form of movement meditation. It takes your mind off of whatever is bothering you and can refocus it on your body’s movements or your breathing when doing physical activity, which is exactly the goal of meditation. This can increase your energy levels and optimism while reducing stress.
It reduces negative side effects of stress - Ordinary activity is an easy way to better your mood, improve self-confidence, and help you relax, eliminating the negative aspects that come with stress. Exercise can also improve your sleeping habits, which is often disturbed by stress.