We can get more if we will, because there is more real understanding of the science of hygiene than our fathers and mothers had before us.

Our need now is to use _practically_ the information which a few individuals are able to give us, and especially to teach such practical use to our children.
Let us find out how we would actually go to work to keep rested, and take the information of plain common sense and use it.
To keep rested we must not overwork our body inside or outside.

We must keep it in an equilibrium of action and rest.
We overwork our body inside when we eat the wrong food and when we eat too much or not enough of the right food, for then the stomach has more than its share of work to do, and as the effort to do it well robs the brain and the whole nervous system, so, of course, the rest of the body has not its rightful supply of energy and the natural result is great fatigue.
We overwork our body inside when we do not give it its due amount of fresh air.

The blood needs the oxygen to supply itself and the nerves and muscles with power to do their work.

When the oxygen is not supplied to the blood, the machinery of the body has to work with so much less power than really belongs to it, that there is great strain in the effort to do its work properly, and the effect is, of course, fatigue.
In either of the above cases, both with an overworked stomach and an overworked heart and lungs, the complaint is very apt to be, "Why am I so tired when I have done nothing to get tired ?" The answer is, "No, you have done nothing outside with your muscles, but the heart and lungs and the stomach are delicate and exquisite instruments.