Mr Li is not a doctor or a nurse, but he knows the secret to good health. He is 80 years old but looks only 60. He says you can do some simple things to stay healthy. First, get plenty of sleep, at least 8 hours each night, so you will feel good for the next day. Second, keep a good diet. Eat more vegetables and less meat. Don't eat too much sweet or oily food. And drink tea or water, not coke or coffee. Third, take plenty of exercise. Mr Li walks for one hour in the park every morning and sometimes dances with his friends there. Finally, Mr Li thinks the most important thing for a healthy life is to be happy. He never worries too much and always has a smile on his face. That’s why, even at 80, his hair is still black and not white.