How to keep healthy
Nowadays students' physical fitness is declining year by year.
I think there are some reasons. 
Students have too much homework to do, so they have little time to
have sports. Some students eat too much junk food. That's also bad for their health.
Then, how to keep healthy? Here is some useful advice. First, students should
do more exercise. Second, students should eat a balanced diet.
They should eat more vegetables and fruits, and try to eat less
junk food. Finally, enough sleep is also very important.