This is a concept of Chinese medicine. Chinese medicine believes that in spring and summer, the yang will grow, and the yang will reach the body surface from the inside out, while the yin will gather from the outside to the inside. At this time, health care should encourage yang to stay outside. At this time, you should eat more spicy, fire-reducing and hot food and exercise more to promote the "exercise" of yang! Nourishing yin in autumn and winter means that the sun is the yang inside and the yin outside. At this time, don't eat spicy food, but increase acidic food to help convergence! Health preservation is a principle that a university requires TCM to maintain health in four seasons, such as nourishing yang in the morning and nourishing yin at night, nourishing yang in spring and summer, nourishing yang in autumn and winter, and so on. It needs long-term persistence according to personal physique to achieve results. For example, drinking a cup of "ginger and brown sugar water (hot)" to nourish yang in spring and summer morning will help yang to rise to the body and provide heat source (power), and drinking a cup of white radish juice (white sugar can be added) in the evening will help yin to converge, while eating a piece of vinegar soaked ginger or drinking a cup of honey Jiang Shui (warm water) in autumn and winter morning are all good ways to avoid yin! In short, in spring, it is necessary to store bitterness and increase sweetness (eat more sweets and less spicy food in spring), in summer, it is necessary to store bitterness and increase saltiness (eat less salty food and increase sour food), and in autumn, it is necessary to store saltiness and increase bitterness (eat less salty food and increase bitter food in winter).