Hikers around the world are rediscovering Spain's Camino de Santiago, Medieval Europe's version of the thru-hike. A veteran of the pilgrimage shares his tips for getting your boots on the path.

This story appears in the May 2015 issue of National Geographic magazine. During the summers of 2012 and 2013, I walked more than a thousand miles on the Camino de Santiago. Also called the Way of ...