根据短文内容和首字母提示，在下文空格处填入适当的词使短文完整。（每空一词）
Everyone knows that exercise is important. We all need to exercise. Doctors say i _____   is good for us. It makes your heart and body s_____. Children who often exercise are more alert（灵活的）. This means they do better in tests and schoolwork than those who don’t exercise.
There are many w______ to exercise. You can walk, run, swim, skate, or play ball games. Make sure you e_____ in the following ways: you have to like what you’re doing. Exercise enough --- but not too m______. It’s best to exercise t_____ each week. Thirty minutes each time is enough. Try all kinds of things until you find one, two or even three sports that feel r____for you.
You can exercise at fitness centers (健身中心). They have l______ of equipment （设备） there . The equipment will help exercise your arms, legs and other parts of your body to make you f ______. Some people buy equipment for their homes. But it is very expensive.
Exercising can be fun. Friends can exercise t _____ at a fitness center, or they can play sports together. How do you exercise?