As we age, we have a little bit less of everything: less energy, less physical flexibility, less learning capacity. That’s why the concept of multiple reserves is so important. Aging well isn’t just about avoiding death and disease. Aging healthy also means keeping the reserve capacity of our component systems high so that, as function declines with age, performance is less severely affected, and fitness is better maintained. The body’s organ systems are all interconnected and interdependent. And the brain is dependent upon the healthy functioning of all organ systems. It needs to be a goal of our aging to enhance the possibility that negative interactions do not take place. In order to pursue this goal, we need to manage our lifestyle activities so that our fitness levels can be enhanced. By this I mean fitness in the sense of interdependence—fitness of all the body parts, not only one of them. The good news is there are lots of things everyone can do to maximize healthful interactions inside our body and between ourselves and friends, family, and community.