You are a long-distance animal.

Humans spread out of Africa and kept going until we had reached almost everywhere there is — deserts, rainforest, mountains, ice, and eventually islands far out in the ocean. Most of that was done on foot, over thousands of years, by people walking.

That takes a particular kind of body, and it is not a fast one. Almost any animal your size will beat you over a hundred metres, and it will not be close. What you are built for is duration. You have long legs, and tendons that work like springs — they return some of the energy of each stride, so the next one costs you less. You sweat, which means you can shed heat while you are still working. Most animals cannot. They have to stop and lie down in the shade through the hottest part of the day, and you do not.

It is not only running. Walking, swimming, climbing, carrying something heavy a long way — we can keep going at all of them, and that is the thing we are actually good at.

You still have that body. It is the one sitting in your chair right now.