First of all, if you want to build strong muscles, you must ensure that you have enough to eat every day (balanced diet, supplement protein) and get enough sleep, otherwise it is useless to practice again. On this basis, I suggest you go to the gym, where you can know what you want, and only there is a full set of equipment. If you don't have time or a gym nearby, you should buy at least a pair of dumbbells and practice every two days. You can find the specific exercises online. good luck

In other words, if your goal is self-defense, you still have to practice martial arts after you get strong. I suggest you learn extreme karate, boxing, Sanda and other martial arts that attach importance to actual combat. The technique of vest can also be used (Israeli self-defense), and there is no place to learn it in China.