2. _Take Exercise_--If you have watched soldiers obey commands in drill you know how quickly their joints and muscles work. The setting-up exercises given in the Handbook have been planned to preserve the power of joints and muscles, and to prevent them from becoming like rusty machines. These exercises should be taken with windows open, if not out of doors. Clothing should be light and loose, and corsets removed. These exercises are not to be considered a substitute for vigorous outdoor work or play, but only as supplementary to or when these are impossible. The day should be planned to include at least an hour and a half of vigorous activity in the open air. This will take different forms, according to the place and season, so that in the summer one may swim, row or paddle, or play tennis or any other game outdoors, and in the winter skate, coast or snowshoe. However, the best all year round exercise, and the simplest and easiest to get is walking. Five miles a day is an adequate average. Even walking alone is good exercise, but walking in a group or two and two is better, because keeping step, singing, whistling and talking and laughing together add enormously to the exhilaration of motion and of sun, wind or rain in the face. A Girl Scout should avoid unusual exercise before, during and immediately following menstruation. However, she should remember that a reasonable amount of exercise at this time is quite normal and beneficial, except where there is an actual disorder of some sort. In this case a physician should be consulted. 3. _Rest and Conserve Energy_--Go to bed early and sleep from eight to eleven hours, according to age. Sleep with windows open all the year round. Rest sometime during the day, flat on the back if possible, but even five minutes sitting quietly with hands in the lap and eyes closed is better than nothing. The following table shows the number of hours of sleep that are needed at different ages: _Age_ _Hours of Sleep_ 10 and 11 years 9-1/2 to 11 12 and 13 years 9 to 10-1/2 14 and 15 years 8-1/2 to 10 16 and 17 years 8 to 9-1/2 18 and 19 years 8 to 9 20 and over at least 8 Save Your Eyes