Why Exercise is so important
The twins' brains also were unalike. The active twins had significantly more grey matter than the sedentary twins, especially in areas of the brain involved in motor control and coordination.
Presumably, all of these differences in the young men's bodies and brains had developed during their few, brief years of divergent workouts, underscoring how rapidly and robustly exercising — or not — can affect health, said Dr. Urho Kujala, a professor of sports and exercise medicine at the University of Jyvaskyla who oversaw the study.
Great article on the New York Times
You may notice I'm pretty enthusiastic about the idea of exercise - it's not just for the adrenaline rush!
I love the idea of getting high on cliff faces for fun, but I also love the exercise benefits from the sport - the creativity to work out how to climb up the wall using whatever the rock gives you (and thus giving a mental challenge), as well as the physical exercise.