Our brains, like the rest of our bodies, develop from newborn to older adult in response to their experience of their environment. Many brains establish strategies for dealing with the world that slow down or even block parts of its development. As they age, our brains can also become less flexible and responsive as metabolism and blood flow change. Memory, thinking, learning, even emotional brightness can all be affected. Brain-training—like other physical exercise—can not only release old habit patterns and increase our options, it can improve the physical function of aging brains as well.