In school, phys ed was a horrible experience. I had no love for team athletics, so I came to the false conclusion that I was inherently bad at sports. What's more, I was teased for being a "book nerd," even by the teachers.

So I was alienated from almost all athletics. I avoided any real physical activity well into my 20s.

There was one exception: In high school, I tried Cross Country, mostly because I wanted to hang out more with my best friend, who happened to be a runner.

After college, I dabbled in 5Ks and 10Ks—in part because my first boyfriend was a runner, and in part because if you live in Madison, Wisconsin, you are contractually bound to be a distance runner. (I'm kidding, of course, but there are so many runners out on the city roads that it sometimes feels that way.)

Finally, at age 30, I picked up the book that would change my life. In Marathon: You Can Do It, Jeff Galloway talks about how one-minute walk-breaks on long runs can extend your running endurance—and even improve your overall time.

Apparently, walking uses your muscles differently than running, allowing you to rest up during your run. Wow. Who knew?

I wasn't confident that I could complete an entire marathon, so I aimed for a half marathon. And, in 2007, I did it! Once I had run 13 miles, adding more miles no longer seemed impossible.

I completed my first of four marathons the following year.

These days, I no longer run marathons. I've moved on to harder and more challenging goals. I've completed triathlons and a decathlon. And I've picked up volleyball, kickball, and weightlifting, too.

That former kid who avoided phys ed and sports of any kind? He's long gone now… thanks to the one book this "book nerd" finally picked up!