Weight-drop and fight cardio can come from taking a martial arts class. Definitely work the muscles more, whether through isometric body training or through weight-lifting, whichever you prefer.
Once you have some skills built up, sparring is absolutely key. It gives you a real-life use for the mess of crap you learn in class and it feels really good the first time you slug a friend in the face with an upward elbow!
Nutrition is crazy important. Protein is absolutely the most important, Complex protein because it actually produces more protein molecules in the muscles over time. Just cuz a McDonalds doube cheese has 50grams of protein doesn't mean a damn thing because there's so much fat in it you're wasting your time. Compex-carbs are a big help as well and depending on the variety of protein intake are key to activating the complex proteins.
Remember MAD CARDIO!
At all times perform cardio. If you have to walk to the store, run there. If your school is only a few miles from home, run there. Even if you can't do it all at once, run in spurts. It burns fat and builds endurance.
Anyone with the motivation and drive can fight. Hell when I was in high school I weighed 300lbs. Now Im 202 and lean. It takes time and effort but is more than possible.