Everyone needs helps and everyone can help others.
For example.If one day,your classmate is on duty.Maybe you will help him to clean the classroom.But you may ask me why you should help him?
When you are on duty,but you have to go home,then what are you going to do?I think maybe you will ask your classmates for help,and they may glad to help you.Just because once you have helped him.
Helping him to clean up the classroom also can make the classroom get bright and clear.It can make you and your classmates feel good in the classroom,then you may get good grades.
So you see,helping others is helping oursevles!