People are busy working every day, so they do not have enough time to do exercises. As a result
(结果), many people become too fat or too thin. To keep our bodies healthy, we have to do exercise
every day.
     There are many kinds of exercise. Bending (弯腰) and stretching (伸展) helps us move easily. Before
we play ball games or swim, it is better for us to do bending and stretching exercise first. This kind of
exercise is sometimes called warm-up exercise. Running is also a good exercise. If we cannot run fast,
we can jog. Jogging means running slowly. Again, before we run or jog, we must do warm-up exercise.
Also, we should not run or jog in busy streets. The air there is often dirty. Some people like weight lifting
(举重) because it can make their bodies strong. Also, we need to do some warm-up exercises before
weight lifting.

A. Eating or drinking too much
B. Having no time to do exercise
C. Doing more exercise
D. Reading at home