The first time I talked my wife Kristin into going for a run with me, it was around the 1/4-mile high school track by our house in Boulder, Colorado. After the first lap, she had to take a break, partly due to the altitude (she’d just moved out from Philadelphia), and partly because she hadn’t done much in the way of physical activity in her 25 years of life. I don’t think we made it to a mile that day.

Despite at first hating that oh-so-special feeling of heart, lung, and leg exhaustion you get from running, Kristin didn’t give up. She felt it was important to get active and live a healthy life. Plus, we were in Boulder — it just felt natural to do as the Boulderites did.

Over the years, we had an on-again, off-again relationship with running, and Kristin eventually got fit enough to run three or four miles without keeling over. Then, about four months ago, unprompted, she declared she wanted to run 10 miles, whatever it might take. We Googled up a basic training program and started running four days a week, with increasingly longer runs on Sunday. We’d rise at 5:45am to beat the summer heat, pull on our shorts and lace up our shoes, and hit the road. The runs didn’t always feel great while we were doing them, but we always felt refreshed afterward and into the workday. Kristin got hooked on that feeling, the way most people do if they stick with running for long enough.

Just over a month ago, we made it to eight miles, but then Kristin tweaked her foot. She finished her run that day but could barely walk the final block back to our house. She was despondent, afraid she’d never get to her goal. “Maybe my body isn’t made to run 10 miles,” she moped.

We started up running again last week. We ticked off one three-miler and then, on Sunday, halfway into a planned four miles, we decided to just go for it. Nearly two hours later, we finished the elusive Mile 10.

We certainly didn’t break any speed records that day, but we finished, and pretty much off the couch, too. I know: people run 100 miles across Death Valley in the summer, so in the scheme of things, our 10 miles was not what you’d call a “big deal,” but what’s important is that Kristin set a goal for herself, a goal that at the time seemed distant, and she worked until she met it. Sunday’s run was, for her, one big step towards learning to ignore the niggling gremlins of self-doubt that plague us all. Genuine confidence (and, dare I say, happiness) is built on a foundation of moments when you did what you set out to do — when you did more than you thought you could.

Sure, I’m happy — I haven’t run 10 miles in many a year — but I am most proud of Kristin. She is now 10 miles closer to understanding that, with hard work, confidence, and a willingness to just fucking try, all things are possible; nothing is unpossible.

The only question now is, which half-marathon should we do?