The old cliché "use it or lose it" really has a lot of truth to it. Our body (which includes our brain) is not designed to be "happy" as a physically and mentally inactive "couch potato"; it needs exercise of both muscle and neural tissue to maintain its health and to attain its maximum possible longevity. In fact in our opinion, exercise of the body and brain is second only in importance to food in respect to its effects on health and longevity. The only debate surrounds just what are the optimal types and amounts of such exercise, and whether too much exercise, including that which creates extra body mass, can lead to a reduction of health and longevity.
In this section, we present the theory and practice of body and brain exercise which current scientific evidence has convinced us is most conducive to a healthy, happy and long life. Individual humans have enormous genetic variation which is additionally compounded by the alterations of development and the modifications wrought by external insults during a long life-time. In addition, they have a life-time of highly varied acquired tastes regarding their activities. Therefore, no one regimen of physical and mental exercise types and amounts will be either satisfying or optimal for the health and longevity of everyone. We make allowance for that by suggesting alternatives, within reasonable bounds, which we think can fully satisfy the needs of both the body and the mind while still being compatible with the happiness of the individual.
The types and amounts of exercise of brain and body which are optimal for health and longevity can only be determined from the benefits and harms which are shown by experimental research to accrue from those types and amounts of exercise. A study of the research literature strongly suggests that moderate amounts of the following four basic kinds of non-brain exercise are needed.
Various exercise methods will be compared with respect to what extent they fit into one of these four types. In addition, research results will be brought to bear on the question of what amounts of each of these types of exercise may be optimal. As stated above, this last is the most contentious question and a final decision must be left for each individual to decide based on his own individual physiological parameters and acquired tastes.
The subject of brain exercise and its effects on health and longevity, let alone on various measurements of intelligence and brain ability, has been much less researched. However, brain power appears to divide itself into the following possibly largely independent categories which may be benefited by separate kinds of exercise.
The brain is such a highly complicated organ and set of processes that it is clear from a scrutiny of the above categories that each in turn divides into several quite distinct others. This general topic of how the brain works is discussed in more detail in the Cognitive Science section (not available yet). Under this Exercise section, we will only give examples of types of activities which may strengthen each of the above categories of brain function and we consider scientific evidence that such activities will benefit both health and longevity.
It will be stressed that the best exercises of body and brain are not those of a contrived, game-playing nature, but instead are attained by the use of the body and brain for productive purposes. By best we mean that which optimizes one's long-range health, happiness and lifespan. The nature of such natural productive activities is described and examples are given. Finally, individuals are urged to reorient their lives to have these kinds of productive exercise of mind and body occur naturally in the course of their daily activities.