What I did in Jr. High was push-ups and crunches. Figure out how many you can do at first. Then do slightly less than that in sets. For me, I would do 25 pushups, 50 crunches, 25 knuckle pushups, 50 side crunches, 25 fingertip pushups, 50 (other) side crunches, then 25 regular pushups, and 50 regular crunches. You can do those types of pushups, or also include wide-arm pushups, triangle or diamond pushups, or elevated pushups. Mix it up. Be sure to include lots of healthy food in your diet. In order to build muscle, you have to go into a caloric excess. This means you have to take in more calories through your diet than what you burn exercising. Get a set of light-weight (5-8 lbs) dumbbells and do curls, military presses, etc. with them. Be sure to include squats (with proper technique) and calf-raises to even out your lower body strength training routine. Bodyweight exercises are a great way to exercise with little (or no) equipment. Activities such as pull-ups, dips, or lunges can help build strength and muscle. Just doing a Google search comes up with many results. You may not be a 6' body builder, but you can still be fit. Football example: Maurice Jones-Drew of Jacksonville putting a monster block on Shawn Merriman of the San Diego Chargers (look it up on YouTube). Also, Bob Sanders of the Indy Colts was the defensive player of the year in the NFL, and he's 5'8". This just goes to show you that good things come in small packages. However, it seems like you haven't hit your big growth spurt yet. There's no way to make yourself taller, but eating well and exercising can definitely help you add some muscle to your frame. When I was in 8th grade, I was one of the few people who could bench press my body weight (155). From 8th grade to 10th grade I put on about 10-15 pounds of muscle. I'm not into body building, but I like to maintain the strength and physique that I have, so I still do many of these activities in variations. I don't like to go to the gym and work out, I'd much rather do it at home. Good luck to you, and send me a message if you have any questions for me. Thanks!