This may be the most worthwhile reason for exercising there is. Studies have shown how people who exercise are at a significantly reduced risk of developing dementia like Alzheimer’s disease. And even for people who start exercising relatively late in life, brain volume can actually increase over time, as can scores on memory tests, compared to people who don’t exercise (their brains shrunk over time, which is normal part of aging).

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.