_Rules for Long Walks._—In walking, not only the distance should be taken into account, but the character of the road and the incline of the ascent. A distance that could be easily covered on a smooth, level highway may mean double the expenditure of muscle and nerve force if the ground is sandy or very damp. Other hindrances to be taken into consideration are opposing winds, not only because of the resistance, but also because of the inhalation of dust and rain. The walk should be occasionally broken for short periods of rest. The pauses should be short, about five minutes, and during this time the body should be erect. Experience proves that sitting down makes one more tired on getting up again. A short halt should be made before climbing a steep ascent, so as to begin with fresh strength and easy breathing, as this means increased work for the heart and lungs. In starting out for a walk, one should begin slowly, and gradually increase the pace, and in returning the same rule should be observed. =Running.=—The force exerted in running is enormous. In running it is the length of the step more than anything else which increases the speed of the run; hence, the runner should learn to take long steps. But the greatest speed can only be kept up for a limited time; the distance is one hundred yards. Running is the most effective of all exercises of speed, and, like all exercises of speed, can be changed into one of endurance by a certain moderation in the pace. By running the heart and lungs are developed more than by any other exercise. _Age Limit for Running._—All ages are not equally well adapted for running: they do not all share in its good results. Running is best for all young people, before and at the age of puberty. Running is then quite a necessity. The growing child is always ready for a run. From the fortieth year on running, as an exercise of speed, becomes less and less desirable, and, when the organs of circulation or breathing are impaired, it must be absolutely forbidden. In running always begin slowly—running moderately, for instance, for fifty feet; then increase the speed gradually, but when running for exercise, never speed to the utmost, as this is not necessary for the benefits of the exercise. Always close the run with the same moderation with which it was commenced; that is, never stop short, as this sudden arrest of action gives a most undesirable shock to the heart. The movements of running may easily be imitated in the house, while standing in one place, and simply lifting the feet in the same quick alternation from the floor.