Hi Stephan, lifting weights as a teenager is great as long as you do it correctly and safeUUly, hire a trainer or educate yourself. There is a great book on strength training for teenagers or young athletes by Wayne Westcott phd and Avery Faigenbaum phd. Just google it and the books should show up on amazon. They also have written several great articles. Be smart and train smart and you will result that do not cause you pain just maybe some muscle discomfort..