Call it the race to quit. It began last year; I was traveling in Sweden when my mom, a former smoker, called and mentioned offhandedly that she had just undergone surgery for atherosclerosis. She went on to remind me that her father, a smoker, had died of hardened arteries, and then she told me something I didn't know: He was 33 when he collapsed.

Being 30 years old, this spooked me. I live in Boulder, Colorado, probably the single healthiest city in the country. I road-bike, I telemark-ski, I've climbed Rainier. And I smoke. About a pack a day for the past decade. I'm not proud of it, but there it is. I never envisioned myself as a 30-year-old smoker. Fresh out of college and traveling around the world, I smoked like everyone else did, sharing stories and cigarettes in the hostels. When I moved to New York City to look for work, puffing away on my stoop became one of the few forms of recreation I could afford, and then once I found a job, the habit persisted, through price hikes, health kicks, and disgusted girlfriends. I tried to quit dozens of times with all the obvious strategies—gum, the patch, cold turkey. On one birthday I even swallowed my pride and asked friends for the one gift I couldn't seem to give myself: motivation. Their sincere, passionate e-mails stuck like Pam. As soon as I felt strong, I'd slip.

But Mom's revelation was different. It hit me like a falling anvil. Suddenly I had an artery-hard deadline.

When I recovered from the blow, an elegant plan took shape. What I needed, I realized, was not to quit something but to start something. So I decided I would run. I'd trade that schizo nicotine buzz for a wholesome runner's high and then celebrate the swap with an elevated vacation at the Nunavut Midnight Sun Marathon, a rugged 26.2-mile course 435 miles above the Arctic Circle in Arctic Bay, Canada. Only a few dozen people fly to the top of Baffin Island to compete each July, and I imagined the treeless landscape—the icy bays, the wide, loamy valleys—stretching out in all directions like a blank canvas, the perfect place to draw a new, smoke-free self. Never mind that the last time I'd actually jogged was at the back of my JV cross-country team. I had my mantra: Run from the addiction.