Exercise is not just about aerobic capacity and muscle size. Sure, exercise improves your health and your physique, but it has even greater benefits for your energy, mood, and brainpower. A study in the ACSM Journal of Health & Fitness asked long-term exercisers (those who had been regularly exercising for an average of 13 years) what motivated them to continue exercising. Rather than being motivated by building muscle or flattening their stomachs,...