1. The most important thing is to ensure that the lower abdomen is not cold! There are knees and other joints, don't sacrifice temperature for grace! 2. Exercise, run, keep fit, sweat more, and don't stay at home in winter. 3. Drink mutton soup. Drink more soup to improve immunity. What needs special reminder is that soup should be cooked with special tools, preferably water stew. Burning it directly is too destructive to nutrition! You can use big-name waterproof stews like Sky Electric.