Firstly, you should exercise. Doing exercise every day can help your body keep healthy.You can do some morning exercise,play table tennis,play baskeball and so on.
Secondly,having the good and healthy food is important,too. I think to keep a health diet is the first important thing.If you want to have a good health body you need to eat more vegetables,fruit,bean and some other green food.
Thirdly,To sleep well and have a good mood are very necessary.If you don't get enough sleep, you will feel tired and you won't concentrate better. You'll need to persevere if you want to have a healthy body.