omg..lol..don't worry about it..i'm 13, about 95 pounds..i'm VERY light...and i'm SKINNY as hell too..well..since i've been working out i've gotten stronger..if you lift weights that will help
but she's right, do pushups and situps/crunches EVERY night and you SHOULD be fine..
iono how much i can bench press...but probably not even 80 pounds..lol..but my punches are pretty strong
btw...are you trying to impress someone or just getting stronger for breakin?