In April 2007, Forbes reported that Dr. Scott Small, associate professor of neurology at Columbia University Medical Center did some research with mice and learned that exercise stimulates a part of the brain to grow neurons that result in improved memory. "If you're worried about memory loss," says Small, "think about doing exercise," he said.
At the American College of Sports Medicine's (ACSM) annual Health and Fitness Summit & Exposition in March 2007, Michael Bracko stated that the mental benefits often outweigh (sorry, couldn't help myself!) the physical improvements. Exercise may not make you look like a supermodel, but you'll feel better, suffer less stress, and sleep better too.
And get this, it works both ways! Ellen Langer, professor of psychology at Harvard Medical School, found that our mental state affects the how benificial our exercise is to our bodies.