Start with high-confidence fitness & exercise books, then narrow by subgenre or adjacent topics.
The Busy Body Book
Lizzy Rockwell
Karate for Kids
Robin L. Rielly
Taekwondo for Kids
Y. H. Park
The Boy's Fitness Guide
Frank C. Hawkins, Gheorghe Muresan
Strength and Conditioning for Teenagers
Mr Arj Thiruchelvam, Arj Thiruchelvam
