Are push-ups bad for a 15-year-old boy?Push ups are GREAT for a 15 year old boy. The thing about push ups, if done correctly, is that it is hard to hurt your shoulders. Damaging your shoulders doing bench press is all too easy. The push up position stabilizes the shoulder girdle in a way that bench press does not. Another cool thing about push ups is, if done correctly, is they, unlike bench, build core strength.
Now don't go all hog wild and start doing a million push ups a day. You can still injure yourself by doing them wrong or doing too many. Learn to do them with good form.