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've got a motto here-you're tougher than you think you are, and you can do more than you think you can.

Perhaps all our troubles - all the violence, obesity, illness, depression, and greed we can't overcome - began when we stopped living as Running People. Deny your nature, and it will erupt in some other, uglier way.

Way before we were scratching pictures on caves or beating rhythms on hollow trees we were perfecting the art of combining our breath and mind and muscles into fluid self-propulsion over wild terrain.

Endurance, after all, is the only reason we even exist. We think of ourselves as nature's deadliest animals, but the truth is, a naked human is the biggest wimp in the wild. We have no fangs, no claws, no strength, and no speed.

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.

We say the rarajipari is the game of life, ' Angel said. 'You never know how hard it will be. You never know when it will end. You can't control it. You can only adjust.