Growing up, I was always a physical kid. I lived in the middle of the woods on a lake in central Minnesota, where the nearest town with more than 1,000 people was 20 miles away. Needless to say, I had to make my own fun, which wasn’t very difficult considering I had ample amounts of nature’s playground to work with. My brother and I would swim and waterski; we would play baseball and volleyball, and ride our bikes around our yard. I also grew up dancing—enjoying many hours of practice each week for more than 14 years. Through all of that activity, though, I never gave any serious thought to running. I dreaded—dreaded—the mile-run in phy-ed class, huffing and puffing all the way around the track. Then, I went to college. I was done dancing and stuffed into a tiny dorm room with a stranger. I decided I would take advantage of...