Getting in shape
  People usually decide to get in shape when they do not like their look or when they do not feel well.
  They may be round where they should be straight or soft where they should be firm, or they may easily run out of breath when climbing a flight of stairs. _____26_____ The body stores fat when the amount of food eaten is greater than the amount needed to give the body enough energy for its activities. _____27_____
  _____28_____ People who usually only use their muscles to sit, stand, and walk short distances usually have very soft muscles. These people do not look badly out of shape, but they still do not look healthy.
  When people exercise little, their hearts do not have to work hard and soon become weak. _____29_____ So they must beat quickly in order to get enough blood to the different parts of the body. When people with this kind of heart do something difficult, their hearts must beat very fast to give their muscles enough blood. _____30_____
  When people exercise regularly, they burn more energy, leaving less to be stored as fat, challenge their muscles, making them stronger and harder, and force their hearts to pump harder in order to supply enough blood in fewer beats. The combination of low body fat, firm muscles and a strong heart makes people look better, look fitter and feel better.
A. People who eat a lot and move very little usually get quite fat.
B. Then these people begin to breathe heavily and soon become very tired.
C. Muscle becomes soft when it is not used to doing difficult work.
D. They will die for going too long.
E. The roundness is caused by fat, which lies over the muscles and under the skin.
F. They do not pump very much blood when they beat