Humans are built for endurance, not speed. We're awful sprinters compared to every other animal. We try to run our races as if they were speed races, but they are not. They're endurance races. Even a marathon, the way it's run now, it's not an endurance contest.

We are the biggest sissies in the jungle. Every other animal is stronger than we are - they have fangs, they have claws, they have nimbleness, they have speed. We think Usain Bolt is fast - Usain Bolt can get his ass kicked by a squirrel.

Every morning in Africa, a gazelle wakes up, it knows it must outrun the fastest lion or it will be killed. Every morning in Africa, a lion wakes up. It knows it must run faster than the slowest gazelle, or it will starve. It doesn't matter whether you're the lion or a gazelle-when the sun comes up, you'd better be running.

You don't stop running because you get old, you get old because you stop running.

If you don't think you were born to run you're not only denying history. You're denying who you are.

Distance running was revered because it was indispensable; it was the way we survived and thrived and spread across the planet. You ran to eat and to avoid being eaten; you ran to find a mate and impress her, and with her you ran off to start a new life together. You had to love running, or you wouldn't live to love anything else. And like everything else we love-everything we sentimentally call our 'passions' and 'desires'-it's really an encoded ancestral necessity. We were born to run; we were born because we run.

There's something so universal about that sensation, the way running unites our two most primal impulses: fear and pleasure. We run when we're scared, we run when we're ecstatic, we run away from our problems and run around for a good time.