There are six chief laws of health. The first deals with the sanitation of our homes and dwellings; the disposal of sewage; the draining of the soil; the laws of ventilation; the supply of sufficient quantities of pure water, and the general hygiene of the community. We support governors and committees to look after this part of the business, so we need not worry ourselves about it.
The second law of health concerns itself with personal hygiene. It tells us how we should wash and clothe ourselves; how we should ventilate our rooms; how to cool ourselves in hot weather, and the means by which the animal heat is maintained in winter.
The third law tells us about our food; how we should eat; what is the best food for man in health and sickness; what we should drink; and other matters connected with the supply of fuel to our bodies.
The fourth law deals with sleep. It tells us its nature; why we sleep. It insists on the necessity of sufficient sleep, and sleep at the right time.
The sixth law deals with the proper education of the mind. How to educate our children. The absolute necessity of mental study for the physical health of our bodies as well as its more important functions.
We have omitted the fifth law, but will now refer to it, and we will devote the rest of this article to its consideration. This law deals with the question of physical exercise.
Physical exercise is as essential to health as is food or sleep; but, because the need of it is not brought home to us so forcibly as these two other necessities, it rarely receives that attention which it deserves. Everyone knows full well that we may eat too little or too much, that we may eat at improper times, that everything that we can put into our interiors is not equally wholesome, that much that we can eat is positively injurious, and that we must eat every day, be the weather fine or rainy. But how few there are who know that the laws of exercise are in every way comparable with these! Most people are aware that we can take too little exercise; some moderate persons likewise know that we can overdo exercise, and that exercise is not equally good at all times. We have met people who know that all forms of exercise are not equally good, and a few who are aware that some forms of exercise are positively injurious; but we have seldom spoken to anyone who would admit that exercise is essential every day in all weathers.
The first question that we will discuss is, how much exercise is needed every day, how much will give the greatest benefit, and how much is positively injurious?
And on the threshold we are met with the greatest difficulty of the whole subject; for persons vary extremely in their endurance of exercise, and a walk which would be insufficient for one person may be infinitely beyond the powers of a second to endure. We cannot lay down a rule in this particular. Every person must find out for herself what amount of exercise she must indulge in daily. For a perfectly healthy girl of sixteen to twenty, three to five miles’ walk daily, or an hour’s bicycling, or, if outdoor exercise is not permissible, half an hour’s gymnastic exercise is the minimum amount of exercise which she should take daily.
Ever so many people have an idea that you can lay in a stock of exercise, as you can fill a coal-cellar, and draw on the reserve when you are too lazy to renew the supply. These persons will tell you, “I do all my walking on one day, so that there is no necessity for me to go out any other day in the week. I walk twenty-one miles on that day, that is three miles for each day in the week, so I am all right on this score.” Now just consider one moment what you are doing, and you will agree with us that your method is not only fallacious, but exceedingly harmful.