At the age of 7-10, you can start doing gymnastics, athletics, swimming, sports dancing, since these sports harmoniously develop all muscles, and, consequently, the skeleton, while maintaining flexibility and mobility. But weightlifting, for example, should be postponed until the skeleton is sufficiently formed to avoid serious injuries and skeletal disorders.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.