It's a hard, simple calculus: Run until you can't run anymore. Then run some more. Find a new source of energy and will. Then run even faster. - Scott Jurek

Nature's arena has a way of humbling and energizing us.

I worried that my vegan diet might fail me. I worried that I'd run out of energy. I worried that the heat might prove too much. True, I wasn't as sore as I had been before going to a plant-based diet, and my recovery time was faster than ever. True, I almost never got congested, and whenever a cold or flu swept through Seattle, sending a lot of other runners to bed, I stayed healthy. And of course, I had battled Mount Si and prevailed, if a man could be said to prevail. I had also gone to California a week earlier and trained every day in the 100-degree canyons. But if you can imagine running 100 miles, you can imagine almost anything.

Every single one of us possesses the strength to attempt something he isn't sure he can accomplish. It can be running a mile, or a 10K race, or 100 miles. It can be changing a career, losing 5 pounds, or telling someone you love her (or him).