Since we're on the subject of exercise and natural longevity today, it seems worth reminding everyone that "use it or lose it" applies just as much to the brain as the body. If anything, keeping your brain in good shape is way and far more important than looking after your body: medical technologies to repair the aging brain are likely to lag behind other regenerative medicine. The human brain is a very complex piece of equipment, and consequently presents a greater challenge for researchers. While cures for Alzheimer's and Parkinson's seem likely in the decades ahead, that still leaves an array of fearsome age-related degenerative brain conditions, both known and unknown. You only have the one brain - so take care of it.