All who wish to be well, and feel well, and keep well, must seek a free and constant supply of air, and strive to obtain it in all its freshness and purity. They must secure it at all times too, at home and away, indoors and out, summer and winter, day and night. If everyone were to do this, the effect on the health and welfare of the nation would be incalculable. They will find it no irksome duty, for before long they will acquire a taste, a longing, we might say a craving for it which will make them wonder how they ever managed to live without it. An appetite for fresh air is one of those propensities we can indulge in without any fear of going to excess. We can revel in it, gourmandise on it, smack our lips over it, and the more we get of it the better we shall be. CHAPTER XII. EXERCISE. Several men were riding home together in a tramcar on their way from business, and were discussing their health, as so many people do nowadays. They were all looking tired and depressed, and on comparing notes found that they were all suffering from the same complaint, “nervous exhaustion due to overwork.” At least, that is what they called it. They were tired when they went to bed, and just as tired when they got up in the morning, and had no energy for their day’s work. Why the latter should have proved too much for them was a mystery, as their hours were not long by any means, and they were all in the prime of life. As a matter of fact, they were not suffering from nervous exhaustion at all, but from poisoning, the result of a sedentary occupation and want of exercise. These men had an excess of waste products in their system, retarding their digestions and clogging their energies. [Sidenote: Exercise at middle age.] It is particularly at or just before middle age that the want of exercise so frequently manifests itself. Most people keep up their games or their walking until the age of thirty or forty. It is after that stage that they tend to settle down and take things easily. If they would only reduce their diet at the same time little harm might accrue, but unfortunately in many instances, as we have already pointed out, they begin to eat more instead of less. The result is that we are confronted with the problem of increased intake and diminished output. We often see men of strong physique who have given up games and reduced their walking to a minimum, and have become moody and irritable, sleepless and depressed.