Fitness can be done at any age, but I suggest that it is best to practice at or after 16 years old. Young people can also practice, but the intensity should not be too great, otherwise it will affect their development. 16 years old can exercise, but the recommended amount is small first and then slowly added until the group is over. The interval between each group should not be too long, and the number of groups should be more. Each group should try their best to be exhausted. Time is the best proof, of course, we must also ensure diet and adequate sleep. Come on? I just finished exercising, too It's 2: 32 in the morning.