The youngest child who learns martial arts from my brother is only three years old and the oldest is only ten years old. They have a fixed time to practice martial arts every day and often go to some martial arts competitions. I bullied him since I was a child, and it was not until he learned martial arts that I stopped bullying him because I couldn't beat him.
Since I learned martial arts, my physical fitness is much better than that of my peers. Now that I am in high school, I can be regarded as a teenager in my youth. He is particularly narcissistic and always wants to show off his eight-pack abdominal muscles in front of me. At school, no one dares to bully him casually.
Some people may think that it is a waste of time for children to practice martial arts. If they practice martial arts with the idea of making him achieve something, the effect may not be ideal, but if they want him to exercise, it is still possible.