In the U.S. military, push-ups are used to measure a service member’s upper-body strength. And because the physical fitness test directly impacts a service member’s eligibility for promotion, what qualifies as a push-up isn’t open for interpretation. There are rules, dammit.
Benjamin Franklin nailed it when he said, "Fatigue is the best pillow." True story, Benny. There's nothing like pushing your body so far past exhaustion that you'd willingly, even longingly, take a nap on a concrete slab.