Several years ago, I had the opportunity to hike Peru’s Salkantay trail that ends at the famed ruins of Machu Picchu. The five-day pilgrimage led my fellow travelers and me past snow-capped mountains, through lush rain forests, and across the raging Urubamba River. The path summits at 15,500 feet above sea level (4,724.4 meters). At the time, I was in my early 40s, so I was one of the oldest people in our group of mostly 20-something college students. Where they seemed to effortlessly skip like young mountain goats across the rocks and gorges on our path, I staggered and plodded along, gasping for breath. Our guide, Carlos, who truly was impervious to the effects of the altitude, would run ahead with the students and then circle back to provide me with company and encouragement until we made it to camp, sometimes hours after our fellow travelers. In those hours alone together on the trail, Carlos and I developed a rapport.