In fact, in the eyes of people at rest and in motion, the length of the universe is different, which is also caused by the speed effect.

For example, people on the ground may see moving people go 50 light-years away and then return at the same speed immediately. It takes 100 years to go back and forth, and people on the ground have already died. But in the eyes of people who are moving at high speed, the distance is not 50 light years, but maybe only 6 light years, and it only takes 12 years to go back and forth. When they came back, they were still in their prime, but their brother on earth had already died.

This means that your time is slower than that on earth, although you don't feel any difference during the exercise. Therefore, although the life span has not really increased, people can quickly reach the future through high-speed sports, as long as they choose the appropriate sports speed, 1000 years later to reach the world needs 1 year.