And further, by these, my son, be admonished: of making many books there is no end; and much study is a weariness of the flesh. Eccl. 12:12
Mental effort without corresponding physical exercise calls an undue proportion of blood to the brain, and thus the circulation is unbalanced. The brain has too much blood, while the extremities have too little. The hours of study and recreation should be carefully regulated, and a portion of the time should be spent in physical labor. . . .
The health cannot be preserved unless some portion of each day is given to muscular exertion in the open air. Stated hours should be devoted to manual labor of some kind, anything which will call into action all parts of the body. Equalize the taxation of the mental and the physical power, and the mind . . . will be refreshed.
The minds of thinking men labor too hard. They frequently use their mental powers prodigally, while there is another class whose highest aim in life is physical labor. The latter class do not exercise the mind. Their muscles are exercised, but their brains are robbed of intellectual strength; just as the minds of thinking men are worked, but their bodies are robbed of strength and vigor by their neglect to exercise the muscles. . . . Health should be a sufficient inducement to lead them to unite physical with mental labor.
Moral, intellectual, and physical culture should be combined in order to have well-developed, well-balanced men and women. Some are qualified to exercise great intellectual strength, while others are inclined to love and enjoy physical labor. Both of these classes should seek to improve where they are deficient, that they may present to God their entire being, a living sacrifice, holy and acceptable to Him, which is their reasonable service.
The health should be as carefully guarded as the character.
From My Life Today – Page 149