i know what a ectomorph is but your talking about a kid here . Most ppl do the mistake of workoing out without having a proper diet. The diet is the key to succes. And Mike tyson started lifting when he was in prision but that dosent mean it contributed to him boxing worse when he came out he maybe just lost the hang of it cause he dident spare or do enough cardio vasculare exercises his condition wasent the best.(and Im not sure but i think he did lift in his prime) Anyways if you want to listen to the vets do it but if you want to add strenght and weight not in fat but in muscels Than do what i told you GET A PROPER DIEt. Some boxers eat anything and thats why they carry around uneeded weight of fat.