It weakens your body so it will affect your performance if you do sport. I’d advise not doing it at all as you have to arouse yourself one way or another, and even if it’s not porn you’re probably sexualizing the girls at your school just to bust a nut. Penis size, bum size none of them matter. A girl won’t sleep with you if she doesn’t like you so be yourself, enjoy your life, have fun with friends and stop asking sexual questions on the student room. Ur 14, enjoy being a child.