I got a person in my group of friends who never leaves me alone, espacialy about my weight. i'm 16 years old 167 cm tall and i weigh 91 kilo's, i'm tryed diets heaps of them, i'm tryed gyms too, nothing sems to work., but anyway my main concern is putting a stop to this kid, and i feel the only way is to smack him one. But i recon if i do it wont hurt him and he'll beat me (this kids not big and strong its a confidents thing with me) my dad always tell me i hit hard, i always seem to hurt him when we spar ( he was a boxer when he was my age) i've been doing karate for 7 months and i feel that my punches are extremly weak, anything i can do to improve these problems?