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.
The skin also serves as a release point for heat. (See “Why Does My Face Turn Red When I Exercise?” for more on that.) When you exercise, your muscles generate a lot of heat, which you have to give up to the environment so your body temperature doesn’t get too high, Hackney says. The heat in the muscle transfers to the blood, which shuttles it to the skin; it can then escape into the atmosphere.