Running Is Bad For You, Still

What's the difference between a long-distance runner and a pronghorn?

...the husky and Arabian horse wouldn't run long distances if not pushed to do so. Animals run because they have to—to eat or avoid being eaten. Man is the only animal that runs simply to do it. Our large brains can convince our frail bodies to keep moving regardless of cost. We may not be the fastest animals, but we can run ourselves into the ground for sport, exhausting our food supply, and making ourselves susceptible to disease, injury and death. That's a feat no pronghorn can touch.