1.The third health lesson I have to learn is this-I must take plenty of exercise.To make the body strong we must use it.The parts that are most used become the strongest，and those we use least will be the weakest.
2.The arms of the blacksmith are ver y strong because he uses them so much.Ours are weaker than his because we use them so much less.The man who works at healthful labour becomes strong，while the idle man becomes weak.
3.The boy who works and plays in the open air grows strong and healthy，but the boy who sits indoors and does not take exercise grows up to be a weak and unhealthy man.It is best to take our exercise in the open air and the sun-light.
4.Games，like football and cricket，are good for boys.
There are also plenty of pleasant outdoor games for girls.When no game can be played，a brisk walk in the open air is quite as good.Briskwalking is one of the easiest and best of exercises，both for boys and for girls.
5.But there are some things we should avoidwhentaking exercise.We should not work or play too long without resting.We should not try to do things that are beyond our strength.When exercise is too violent，it does harm rather than good.
6.A king，who was feeble and ill because of idleness，
asked medicine from his doctor.The doctor was wiser than the king，and knew that it was not medicine but healthful exercise that he needed.
7.He might have told him that it was his own laziness which had injured his health.But he knew very well that the king would not believe this，and he was very much afraid of making him angry.
8.The doctor therefore brought the king two heavy clubs of a strange kind of wood，and told him that these clubs held the medicine for his cure.
9.The doctor told him that he must grasp them by the handles and swing them about till his hands became moist from the exercise，and this moisture would make the medicine act.He obeyed the faithful doctor，and each day he might be seen in the open air at certain hours，working manfully with his magic clubs.
10.His muscles grew strong，his health improved，and he greatly praised the medicine of his clubs and the wisdom of his good doctor.The king never learned from his faithful servant that the clubs were nothing but wood，and that the secret of their wonderful cure was found not in the clubs but in his own healthful exercise with them.
11.Clubs of this sort are often used by boys and young men，and girls also，to make their hands and arms strong.We call them Indian clubs.Dumb-bel ls ，made of wood or of iron，are also used for the same purpose.Inmany of our schools，the children get drill with dumb-bells or Indian clubs，to help in making their bodies healthy and strong.