Yes as you are just 13 yrs old...take nutritious food ,protein rich food like chicken ,fish , pulses ,egg ,milk ,butter. Do Stretching exercises in early morning like skipping, cycling, swimming helps you a lot...Exercise at least five times per week. By using exercises that help with gaining height, you will naturally increase the level of growth hormones in your body. Certain weight training exercises, high intensity sprints and bar hanging can help you achieve this. you must strengthen your abdominal and back muscles first to get the most out of your exercises..Regards.