Your empty gas light
Running on empty is one of the hardest skills to hone and develop. Do you ever push the limits in your car when the gas light says "empty"? How many miles will the car go before it runs out of gas? You should know that so you do not run out of gas. Will it run on empty for 20 miles or 50 miles? At work and life you will run out of gas. How do you know when you are on empty and about to be out of gas? What do you do when your empty gas light shows up? Does your body tell you? Do you take a break?
I can't think of a less productive way of working with no gas. You car will not run without gas and people can not work without gas. Know when your "empty" gas light shows up so you do not run out of gas and crash. For leaders of people, know when you and others are on empty. Let them recharge.