My son is a lean and very tall, but this bothers him. He would like to build muscle, but he wants to know where to begin. I've been recommending stretching and yoga to build flexibility before he jumps into strength training to ensure he has proper range of motion and posture. He, naturally, is impatient and wants to jump into weights. The internet also has loaded him down with the idea that he needs to eat nothing but protein. He is more energy efficient as a teenager because his metabolism is through the roof. I'm trying to help him to develop a holistic exercise and diet regiment to help him be healthy (I could care less about him bulking up). How do I start, though? It's easier for me because I'm older, but with his metabolism and hormones in flux I want to make sure I'm doing right by him. Any advice would be appreciated!