Experiments on elderly rats put in an enriched environment showed that they increased in dimension and activity of brain cells. There were also other changes indicating the brain cells had become more active. What Santiago proposed was, of course, not new. Each must be trained. Each requires exercise.
Age is held at bay, even conquered by remaining active.
What it requires is daily maintainance. The brain might be said to be tireless. And in one sense the body is, too. Both can operate in the basal states indefinitely. The sedentary body, however, is physically circumscribed.