We all need to exercise.Doctors say it is good for us.It makes our heart and body strong.It also gives you more energy .And you will feel better about yourself.It's good to exercise twice a week.Twenty minutes each time is enough. There are many ways to exercise.You can walk,run,play sports or swim.Many people go to special places to exercise.They are called "fitness centers ".These places have a lot of equipments .People can do different sports there.Some people buy equipments for their homes.But it is very expensive. Exercising can be fun.Friends can exercise together at a fitness center,or they can play sports together.How do you exercise? How often do you exercise? It's good to exercise  _  .
every day 20 minutes a week twice a week twice a month