It's a little cold. I feel very cold when I get up in the morning, and I will be fine in about half an hour. What is the reason?

It's getting cold, not suitable for morning running! It's foggy in winter morning, and people will be short of breath after exercise. If you inhale a lot of fog, it will be bad for your health. . . . Exercise doesn't have to sweat to be effective. Persisting in exercise will always have an effect, but in winter, skin pores shrink and sweat is not easy to discharge. . .