It depends on your purpose. Fighting is a full-body exercise, so there is not much requirement for physical fitness, and any physical fitness can be used. But if you take this as a professional training, it may take a long time to improve your physical fitness. My advice to you is not to rush to fight training for the time being, but to start with basic exercises, such as long-distance running, leg press, sit-ups and push-ups. It is best to go to the gym for systematic basic exercises at least three times.