Running is the heart of what it means to be human.

human urine is both nutrient-rich and an effective tooth whitener

That was the real secret of the Tarahumara: they'd never forgotten what it felt like to love running. They remembered that running was mankind's first fine art, our original act of inspired creation. 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. And when our ancestors finally did make their first cave paintings, what were the first designs? A downward slash, lightning bolts through the bottom and middle-behold, the Running Man.

One of the most dangerous and best-kept secrets of the medical profession is the epidemic of anesthesiologists who are addicted to their own drugs.

...there was some kind of connection between the capacity to love and the capacity to love *running*. The engineering was certainly the same: both depended on loosening your grip on your own desires, putting aside what you wanted and appreciating what you've got, being patient and forgiving and... undemanding...maybe we shouldn't be surprised that getting better at one could make you better at the other.

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.

Even Charles Darwin, that human decoder ring of bizarre behavior, found the idea of saving a stranger's life to be a total head-scratcher.