If you want to be strong and healthy, you must pay attention to the following. First, you should get enough sleep, and do morning exercises every day.
Have meals at regular time and do not hurry when you eat. Remember to sit straight when you read and write. Breathe in as much fresh air as you can. When you come home from school, go out into the open air and play for an hour or so. Keep your body clean. Have a cold shower every morning. Wash your hands before meals.
If you do all these above, you will be strong and healthy.