I have similar problems with you. I am 35 years old, and my five-month time has been reduced from 86KG to 7 1kg. I mainly do two events, one is running for 40 minutes, the other is bench press, 200-400 times, from 10kg to 65KG. From last month's 8 speed, that is, 8 kilometers per hour, to 12 speed, 12 speed, I began to have a dull pain in my knee. I have two ways to deal with it. First of all, I must wear knee pads. I can put a thin towel on the knee pads. If I sweat too much, I will slow down to 10 and extend the running time, and the effect is just as good. In fact, bicycles, rowing machines, mountain climbing machines and so on. It's all a lot of exercise, and you think the effect is not good, which should be the reason why the intensity is not big enough. Even riding a bike, if you keep a certain sprint speed and then do it at intervals, it will not be worse than running. However, my favorite thing is running. Running feels great, and the exercise of will is unmatched by people who run for 3 or 5 minutes. The purpose of my exercise now is to stay healthy, not to lose weight. Good luck.