Exercise acts as a temporary diversion to daily stresses and it improves self-esteem. Increased core temperature during exercise may lead to reduced muscle tension and favourable alterations in brain neurotransmitters. Mood improvements may also occur due to the increased secretion of endogenous (internal) opiates, e.g. endorphins. Psychological changes may occur because of changes in norepinephrine, dopamine and serotonin, all hormones which can affect mood and anxiety levels.
It boosts immunity. Regular exercise can reduce your risk of certain serious health conditions, including heart disease, diabetes and some cancers. It can also decrease your chances of developing -- and getting stuck with -- more common illnesses, such as flus and colds. (According to one recent study, colds lasted 43 percent longer for people who exercised once a week or less.)
Whether we’re fully conscious of it or not, we’re always looking for how to be happy. And exercise is one of the most obvious steps to take, as it’s not a coincidence that you feel better after a good workout: It’s science. A Penn State University study found that people who exercised, whether it was a mild, moderate or vigorous workout, had more pleasant feelings than those who didn’t. (1)