Almost any vigorous exercise will enforce deep breathing, and there is no question as to the benefit of the involuntary or spontaneous inhalation and exhalation thus induced. Running and wrestling are types of very vigorous athletic exercises that will compel one to breathe deeply and fully, and will insure a full lung development without special breathing exercises. And this is more especially true if much exercise of this character is taken regularly, day after day, all the year round. But where the occupation and surroundings are such that one cannot indulge in such active pastimes, or where the time for such exercises is necessarily limited, frequent voluntary deep-breathing exercises can be highly commended. About the best example of the proper use of the diaphragm and the natural movement of the abdominal and dorsal region in correct breathing is illustrated in a small child. In nearly all cases an active healthy child will breathe properly, and by studying the movement of his abdomen in both standing and reclining positions you will find that as the breath is inhaled the abdominal region will expand. When the breath is exhaled this part of the body will contract or be drawn inward. This demonstrates very conclusively that the movement or expansion of the body in natural breathing is abdominal, and that the bony framework of the chest should not be involved except when taking full deep breaths, or when breathing hard from the effects of very vigorous exercise.