My son was always the smallest/youngest kid on every team he played for. He had very good control from the start at 6 or 7....and because of that he could throw harder than other kids as he wasn't worried about where it was going. He could just throw strikes. As he got older he never really did any weight training at all. Starting when he was about 5th or 6th grade he became a huge fan of long toss. And by long toss....I mean a lot of long toss. Sometimes 4 or 5 days a week depending on when he could find someone to throw with. His velo increased constantly after that. By the first time he threw with a gun (7th grade I think) he was in the low 70's. By his sophomore year (5'4 and maybe 100 lbs) he was 82-83....and hit 90 for the first time the end of his junior year of HS baseball. He went to college as a PO...and even then did as little lifting as he could get away with....and continued long tossing. He was up to 93 his sophomore year in college. He swears that the long toss was what allowed him to throw that hard. He always thought that the weights were making him "tight" and actually hurting his velo.