Let me give you a suggestion. Just go jogging in the gym for 5- 10 minutes as a warm-up, with a slight sweat as the standard. Rest for a few minutes after running, and then start strength training as planned. Finally, end with jogging. If the goal is to lose fat, the last jog should be 30-50 minutes. If you are not very fat, it is ok to run for about 20 minutes for the purpose of gaining muscle.

I hope the above answers can help you.