he will use his muscles until they are
strong enough to hold his shoulders back.

=192. How exercise makes the body healthy.=--When you use your
muscles, you become warmer. Your face will be red, for the heart sends
more blood to the working muscle cells. You will be short of breath,
for the cells need more air. You will eat more, for your food is used
up. Your muscles are like an engine. They get their power from burning
food in their own cells. When they work they need to use more food and
air. So working a muscle makes us eat more and breathe deeper. The
blood flows faster, and we feel better all over. The muscle itself
grows much larger and stronger.

If we sit still all day, the fires in our bodies burn low and get
clogged with ashes. We feel dull and sleepy. If we run about for a few
minutes, we shall breathe deeply. The fires will burn brighter. Our
brains will be clearer, and we shall feel like work again. Boys and
girls need to use their muscles when they go to school. Games and play
will make you get your lessons sooner.

=193. How to use the muscles.=--You should use your muscles to make
yourself healthy, and not for the sake of growing strong. Some very
strong men are not well, and some men with small muscles are very
healthy. Some boys have strong muscles because their fathers had
strong muscles before them. Strength of muscle does not make a man.

You ought to have healthy muscles. Then your whole bodies will be
healthy, and you can do a great deal of work. You ought to learn how
to use your muscles rather than how to make them strong. An awkward
and bashful boy may be very strong, but he cannot use his muscles. A
boy is graceful because he can use them.

The best way to use your muscles is in doing something useful. You can
help your mother in the house and your father at the barn. You can run
errands. You can learn to use carpenter's tools or to plant a garden.
Then you will get exercise and not know it. You will also be learning
something useful.

Play is also needed. Work gets tiresome, and you will not want to use
your muscles. Play is bad when it takes you from your work or when you
hurt yourself trying to beat somebody.

=194. Alcohol and the muscles.=--Men use alcohol to make themselves
strong. It dulls their weak feelings, and then they think themselves
strong. They are really weaker. The alcohol hinders digestion and
keeps food from the cells. Then the fires in the body burn low, and
the