I agree with TPM, not sure about all the gimmick stuff. Tee/cage work. I'd guess you have your kid thinking way too much at the plate
I'm not sure how the feel good stories are going to help. I'd assume you're going to show him and be like "see everything will be fine" ?
At 13U you have puberty coming and that's the big unknown Three years from now he might have gained a few pounds, grown a few inches and be "the man". Or not.