You can't run too fast. If you haven't done any exercise training before and are heavy, I suggest you don't rush to run, which will be harmful to your health, especially your heart and joints.

When you start running, don't be impatient. You can combine walking and running. Walk for 2 minutes, run for 2 minutes, and keep running for 30 minutes until you can walk for 2 minutes, run for 15 minutes, and keep running for 40 minutes to 1 hour. This period may last 4-6 weeks. Then you can run for more than 30 minutes-40 minutes. Continuous jogging can burn more fat than short-term high-intensity exercise.