What's a great diet and workout plan for a 16 year old? Without having to go the the gym.?

Run long distances (start short if you're inexperienced - gradually run longer and longer distances), sit ups, push ups, pull ups (at some local park's monkey bars or something), planks, leg lifts, bicycles, Russian twists, bicep curls with some type of weight in your hand, crunches. Diet wise, eat a well balanced meal of veggies, meat, dairy, etc. If you want to tack on some muscle, eat lots of protein, like meat. I've read somewhere that all the sugar consumed within the first 30 mins of a workout becomes a part of your muscle, and I recommend drinking chocolate milk after you run.