Comment by matwood

> When your heart is pounding for hours and the cortisol flowing, you literally get physically exhausted.

Not only that, when the body enters flight response the brain makes mistakes.

When I started jiujitsu many years ago someone asked the professor what's the biggest difference between a white belt and black belt. He thought for a second and said something along the lines that everyone loses, even black belts. The difference is that a black belt will be calm and able to think of solutions until the very end, whereas someone who is untrained panics, isn't able to think, and makes mistakes.

Staying calm is a lesson for life really.