When burnout shows it's ugly head, I give it one more good kick and withdraw - regroup, recoup, and prepare for the next rally. Try it for a six week cycle, I guess. Reading gets you only so far. Here's the top book, top two sites. Show them the right way, the basic way to perform and why.
Further direction is achieved as they matriculate to weight training.
Age12-13 is just right, again if interest is keen and instruction is wise. Yet another - Bodybuilding can be expensive even though every workout is an investment. Overall they will be a healthy investment and may save you money throughout your life. Quick, convenient fortifiers that lift you, take you forward or at the very least, keep you from sliding back. I count on the above food intakes and don't short change myself by viewing them as costly supplements for the rich and famous and foolish.