From youth to middle, and often to past middle, age, most men are apt to be too closely engaged in the struggle of life to pay due attention to the strength of the body. They may take daily what they consider a sufficient amount of exercise; but the exercise is not calculated to keep the various limbs and muscles, still less the internal organs, in proper working order. Amid the ordinary concerns of life the man may appear strong, even stalwart. But when occasion arises for some special muscular exercise, or taxing the action of some organ, he finds out his weakness.