Hi, I'm 15 and I weigh 140 lbs. I amd 5'9" 1/2. I am in pretty good shape although i have about 1/2 inch body fat on / lower abdomen area when I grab it. Could it be that it's extra skin/baby fat for me to keep growing? dad is about 6 ft. I have been doing sprints at 10mph for about .1 mil then...