I too am a vegetarian. It is important that you are getting enough protein in your diet via beans, soy, etc., and not getting too much fat or simple carbs. Being a vegan I do not eat eggs or dairy either so my protein sources come from rice, soy, peas, and whole grains. Protein powders work well and come in various flavors and bases (rice, pea, soy, etc.)3. Increased fruits and veggies, whole grains, and water is also necessary when you are training as you need those complex carbs to fuel your muscles. As far as fat goes-processed foods are evil and should be avoided at all costs! Check the labels and buy/eat whole foods when possible. Lastly, 13 is an age when your body will be starting to undergo a lot of changes. Pick a healthy goal and stay at or above it as your body grows. It may be wise to enlist the help of a parent or friend to monitor you so that you remain healthy.