Once, Su Dongpo's friend Zhang E took a piece of rice paper and asked him to write a word, hoping that he would write something about health preservation. Su Dongpo pondered for a while, then nodded and said, "I have an ancient recipe for keeping fit and living longer." There are only four kinds of medicines, and I will give them to you today. " As a result, Dongpo's wolf hair splashed on the paper, which read: "Things are rare, going to bed early is rich, walking safely is a car, and eating meat at night." Where is the medicine here? Zhang E asked blankly. Su Dongpo smiled and explained that the key to health and longevity lies in these four sentences. The so-called "things are rare" means that people should not think too much about fame, wealth, honor and disgrace. If they can be generous emotionally, then they will be happy and expect nothing in return, which can make people spend their lives more than wealth. "Early to bed is rich" means that eating well, wearing well and having enough goods will not make you live longer. For the elderly, developing good living habits, especially going to bed early and getting up early, is more precious than acquiring any wealth. "Take it easy when driving" means that people should not pay too much attention to comfort and physical exertion, and should walk instead of riding a horse. More exercise can strengthen the body and dredge blood. "Eating late is meat" means that people should only eat when they are hungry and stop when they are not full, instead of being insatiable about food. He further explained that eating after being hungry, although a simple meal, will be sweeter and more delicious than delicacies; You have to eat reluctantly when you are full, even if the delicious food is in front of you, it is difficult to swallow. Su Dongpo's four "longevity drugs" actually emphasize the importance of emotion, sleep, exercise and diet to health and longevity, and this concept of health preservation is still worth learning even today. Excerpt from Pu Zhaohe's Four Longevity Drugs for You.