It's very cold, so you can't stay outdoors for long. What exercise is appropriate?

One person jumps rope and two people play badminton.

Individual differences and training opportunities: Some people are naturally suitable for morning exercises. When they get up in the morning, there is no problem in exercising. Others can't walk so fast in the morning, preferring to stay late. Interestingly, research shows that no matter when you think you are in the best exercise state, for almost everyone, your body is actually stronger and more endurance before dusk.