Everyone wants to have a strong and healthy body but can not keep exercise and obey some principle.It's like people want to spend money but don't want to maky money. I think there's three principle we should obey to keep our body healthy.The first,we should have a nice sleep everynight ,so we should go to bed early before 10 p.m..The second,we should do some exercise every day no matter how busy we are .The last,We should have a balanced diet,especially don't eat too much rich food.I believe if someone could obey this three principle for a long time.he would have a strong and healthy body and be energetic in his study and work.