If you can run six miles on a summer day, then you, my friend, are a lethal weapon in the animal kingdom.

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

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.

Faced with the almost inescapable conclusion that it had been selling lemons, Nike shifted into make-lemonade mode. Jeff Pisciotta became head of a top-secret and seemingly impossible project: finding a way to make a buck off a naked foot.

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.

If you don't have answers to your problems after a four-hour run, you ain't getting them.

In 'Tarahumara' land, there was no crime, war or theft. There was no corruption, obesity, drug addiction, greed, wife-beating, child abuse, heart disease, high blood pressure, or carbon emissions. They didn't get diabetes, or depressed, or even old: 50-year-olds outran teenagers.