Indeed, it is true. Humans are amazing. Not only in their endurance physically but in their mental capacity to enhance such endurance through physical training.

Whilst I may jest, I, as a man in my early twenties, through hard work, could stay on a squash court for 4 to 6 hours at a time and best most opponents, one after another. I long to have those days of physical prowess back. But, I pissed them away, as only humans can do.