I haven't tried swimming because I can't. I insisted on running 800 meters every night for half a year, and the effect was not obvious. I think the best thing is skipping rope. A week later, I will dance for two hours every night. A week later, my pants were obviously loose. When skipping rope, put your feet together and touch the ground with your toes. When jumping, keep your abdomen closed and adjust your breathing. You don't have to jump very high, you have to jump fast. Jump hundreds of times and have a short rest. The quantity can be gradually increased according to the situation.