The world's greatest skyrunner shares the shoes, fitness tracker, and practices that let him climb every mountain in the Western United States in just 31 days.

When it comes to sheer physical capabilities, Kilian Jornet is as far above other world-class trail runners and mountain climbers as they are above us. This fall, the Spanish skyrunner completed his States of Elevation project, which The New York Times called “objectively absurd.” His completely self-powered mission connected all the 14,000-foot peaks in the Mountain West. He reached 72 summits, covered 629 miles on foot, and biked an additional 2,568 miles while amassing 403,691 feet of elevation gain, all in 31 days. Was it even hard for him? No. Ugh.

We spoke to Jornet after he returned to Norway from States of Elevation, getting to spend time at home with his wife, the world-champion skyrunner Emelie Forsberg, and their three children. Forsberg also joined the team at Nnormal, the gear company that Jornet co-founded with the shoe company Camper. The name combines the words “Norway” and ...