Daily exercise helps one to live longer. The body is like the machine, if the machine is not used, it soon gets rusty and when the machine is rusty it breaks easily. If one does not exercise, the body becomes stiff. In the case of old people, if they do not exercise, the body becomes so stiff in time that they no longer can use the legs in walking. Even if you are very old, you can still take a walk daily in the fresh air.
The mind should be exercised by reading and discussing important subjects. If those who are old would this they would not become childish as many old people do.
Exercise is the key