I run 20 minutes before my 30 minute lift session every morning before work.  My strength sessions conclude with pullups until muscle failure.  A fat bragged that he was just as fit as I am because he had my "routine." He suggested we workout together, so we went to the gym.  He covered 1 mile on the treadmill with no incline.  I covered 3 with 2 degrees.  He spends 25 minutes out of the 30 on his phone.  I worked out for the full 30. It's amazing how utterly inefficient fats are at exercise.  20 minutes on the treadmill can be useful, but not when you are waddling.