We all need exercise．Exercise uses up feed that we eat and keeps the body full of（71）e 　 　．Exercise makes your heart and muscles（肌肉） strong．Exercise also makes you feel r elaxed．If you exercise several times a week，you will stay happy and（72）h 　 　．There are many （73）w 　 　to exercise．You can walk，run，play sports or swim．

（74）H 　 　，most people cannot do this．It is too far from their homes to their offices．They have no （75）c 　 　but to drive to work．First，these people don't have a chance to exercise because they are sitting in their cats for two to four hours each day．Second，driving is challenging，（76）e 　 　in rush hours，and needs too much attention．It makes a person （77）t 　 　out．When these people arrive home after work，they don't want to take exercise．

Some western countries，such as the United States，have problems with exercise．Many people don't have enough exercise．They have to work from morning till（78）n 　 　．so they don't have time to take exercise．

Today，many people in the West are fat，which causes health problems，Doctors say exercise can help people both lose （79）w 　 　and improve their health．So many people are trying to get more exercise．But it takes time to change，and when people don't see a （80）d 　 　right away，they will lose heart and stop exercising．