Nobody can deny the necessity of exercise. In a broad sense, all daily activities are kinds of exercise, but in general exercise refer to activities requiring physical efforts.
Exercise is adjusting the movement of qi, by moving muscles, such as limbs, to affect the deep qi in the body.
When qi moves, heat is produced and the body gets warm and the adjustment of its work refers to that the heat spreads all over the body evenly. Good exercise can maintain this state for a long time.
*This article is translated from "Yamai hitokuchi Memo" written by Shoji Kobayashi, 2005.