look up FitnessBlender on youtube, they have a bunch of videos on everything from healthy eating to specific workouts. In terms of body positivity they also offer a wealth of advice. I would recommend watching "Kellis before and after story". Also, middle school can be rough, but just remember that you're great the way you are. Hope this helps!
First, your problem isn't the way you look. The problem is your self-image, the way you think. You're young, we were all bullied at one time or another by someone who was tougher than we were, but if you really want to toughen up physically, study martial arts. I would recommend kung fu, because it's got a spiritual side the others don't because its origins were of a religious nature -- probably not your religion, but Taoism and Buddhism have a lot of practical things to offer as to how to focus and think and be at peace with yourself and the world. Then, of course, never use it -- fighting doesn't make you tough. But knowing how to use your body will help you and get you fit and strong at the same time. And think of life this way -- if you wear shorts or don't, you still look the same. You still are the same. If they make you comfortable, then wear them. If you want to wear them just because you think you should, then don't. It's all in how you think. Now, you don't say what your looks really are -- you don't say if you're overweight or thin or if you're healthy or not or if you're doing well in school or not or if you're having fun or have friends. You don't say how much you're being bullied and how badly, and also whether or not you've bullied others from time to time. When you're young, you usually have periods where you're in with the bullies and times when you're on the outs with them. You will outgrow most of this. I assume what you eat depends on what your parents prepare for you, so if you want to eat healthier they're the ones to discuss it with. It is nice to be good looking, but if you look at the people we admire most over the ages, most of them weren't particularly attractive. They were, however, clever, creative, and driven.
First things first, you should WANT to be exercise, not because of what people at school say, but because it makes you into a healthier person.
So, you never told us whether you think you are too overweight or too skinny.
Either way, you should begin to go to the gym, lift weights, do cardiovascular exercises, and eat a healthy, balanced diet of complex carbohydrates, unsaturated fats, protein, and vitamins and minerals.
alena2504 don't take to much stress on a such a thing..just eat healthy food and do exercise or yoga as u preferred..and important think to stay positive it will automatically increase your confidence level high.