A couple of years ago, I got the urge to write a book. I’d recently returned from a sabbatical in Europe, where my husband Eric and I walked a thousand miles on the Camino de Santiago, a network of pilgrimage trails that date back to the Roman Empire. (You can read more about that on my personal blog, Camino Times Two.) I hadn’t intended to write about the trip when I left, but when I got back I couldn’t shake the suspicion that there was something book-worthy in the experience.

I’d worked in...