It is essential, if you wish to breathe in a perfectly healthy way, that the physical machinery used in the act should be kept in good condition. You must keep your spine moderately straight, and the muscles of your chest must be flexible and free in action. You cannot breathe in the right way if your shoulders are greatly stooped forward and your chest hollow and rigid. Sitting or standing at work in a slightly stooping position tends to produce hollow chest; so does lifting heavy weights--or light weights. The tendency of work, of almost all kinds, is to pull the shoulders forward, curve the spine, and flatten the chest; and if the chest is greatly flattened, full and deep breathing becomes impossible, and perfect health is out of the question. Various gymnastic exercises have been devised to counteract the effect of stooping while at work; such as hanging by the hands from a swing or trapeze bar, or sitting on a chair with the feet under some heavy article of furniture and bending backward until the head touches the floor, and so on. All these are good enough in their way, but very few people will follow them long enough and regularly enough to accomplish any real gain in physique. The taking of "health exercises" of any kind is burdensome and unnecessary; there is a more natural, simpler, and much better way. This better way is to keep yourself straight, and to breathe deeply. Let your mental conception of yourself be that you are a perfectly straight person, and whenever the matter comes to your mind, be sure that you instantly expand your chest, throw back your shoulders, and "straighten up." Whenever you do this, slowly draw in your breath until you fill your lungs to their utmost capacity; "crowd in" all the air you possibly can; and while holding it for an instant in the lungs, throw your shoulders still further back, and stretch your chest; at the same time try to pull your spine forward between the shoulders. Then let the air go easily. This is the one great exercise for keeping the chest full, flexible, and in good condition. Straighten up; fill your lungs FULL; stretch your chest and straighten your spine, and exhale easily. And this exercise you must repeat, in season and out of season, at all times and in all places, until you form a habit of doing it; you can easily do so. Whenever you step out of doors into the fresh, pure air, BREATHE. When you are at work, and think of yourself and your position, BREATHE. When you are in company, and are reminded of the matter, BREATHE. When you are awake in the night, BREATHE. No matter where you are or what you are doing, whenever the idea comes to your mind, straighten up and BREATHE. If you walk to and from your work, take the exercise all the way; it will soon become a delight to you; you will keep it up, not for the sake of health, but as a matter of pleasure.