I first became aware of Dean Karnazes a few years ago shortly after moving back to New York. That was when he came into the spotlight for a lot of people, shortly after he won the Badwater Ultramarathon. In my small running circle, I spread word of his infamy, of the man who ordered pizza for delivery on his all night runs. How he would run a hundred miles just to get to the start of a marathon. How he ran a 200 mile relay race--by himself. Most of what I knew of him came from short articles in running magazines or interviews on NPR. In gearing up for this year's marathon season, I borrowed this book from a friend to find out more about the Ultramarathon Man--who in 2006 ran 50 marathons in 50 states in 50 days; who was the first person to run a marathon to the South Pole--in running shoes; who ran 350 miles without stopping. I wanted some inspiration to get me through the dark moments of my running, when the pain sets in and I feel like I just can't move any further. It helps me in those times to think of someone who went further, who did more, who ran faster or harder and dug deeper to keep going even under the most dire conditions.

Karnazes talks about his early life as a runner, his introduction to the sport by his first track coach, Coach McTavish. Coach's advice was simple: "Go out hard and finish harder." That would be a mantra that Karnazes would take with him throughout life. He seems to be a man full of energy and determination. An article in the New York Times before the 2010 New York Marathon talked about the determination of professional runners. "Mental Tenacity separates the mortals and the immortals in running," the article says. Karnazes must have more mental tenacity than anyone on earth. He pushes himself to extremes just to see if he can. When he feels himself unable to go on, he digs deeper inside himself and finds strength where mere mortals would falter. As a runner, he has pushed the limits of what a human can do. He's pushed the limit so far it seems unlikely that anyone will challenge his feats anytime soon.

What makes this book stand out, though, is the humility with which Karnazes tells his story. He writes with an unexaggerated, self-depracating style that belies the feats he has accomplished. He's the first to admit that he is only human, that he too falls sometimes. One of his most spectacular falls occurs when he runs his first 50 mile race to qualify for the grueling Western States 100. Karnazes describes the events immediately following that race with objective clarity, as though he were telling the story of what happened to a guy he knew. The pain he puts himself through would make most of us cringe in terror, but to him it is just another day. He's a normal man with a normal family and kids who want him to play with them. Immediately after running 200 miles, his kids drag him to an amusement park and he spends the next several hours riding roller coasters. I can't imagine that. After running that distance, I can imagine that all I'd want to do is collapse in a bed.

For all the humility with which he recounts his story, he is seemingly not a very humble man. In recent years he has made very public his aspirations, from running 50 states in 50 days to his very public declaration of wanting to be the first person to run 300 miles non-stop. (That feat was thwarted by Pam Reed, who for two years won the Badwater Ultramarathon and quietly and without much fanfare ran a 25 mile loop 12 times shortly after Dean attempted his record breaking run.) The ultrarunning community is small and rather protective of itself. Dean is an everyman who seems to believe that anyone can run these distances. He has opened ultrarunning to the wider world.

None of that changes the power of this book, though. While it may be ostensibly about running, it is more deeply about following your dreams. Karnazes wants each of us to realize the power of our dreams, to not just have them but to strive to attain them--no matter what they be. For Karnazes, the dream and the passion meet at running. He wants to push his body and his mind to the limit and he works hard every day to do that. It's not easy. I think he makes clear how hard it is to run the distances he runs. But that is the point, he says. "Dreams can come true," he tells his kids, "especially if you train hard enough."

That may be the best takeaway from any book I've read.