In August 2012, my companion, Ann, and I took a hiking trip with five other couples to the Inca ruins of Machu Picchu. Each evening, we would bunk down in a modern, rustic eco-lodge.

The nine-day trip involved hiking about 52 miles in six days through Peru. We are both in our mid-60s and fairly physically fit and active. However, there were many challenges on this trip: hiking 8 to 10 miles each day; adjusting to a high altitude of 15,000-plus feet; multiple changes in climate; eating local, unfamiliar foods; and avoiding injury.

After spending two days in Cuzco, the ancient City of Gold of the Incas, altitude 11,000 feet, we met up with our tour guides.

Our first hike was an eight-mile, ascending trek to our first lodge at 12,690 feet. We were accompanied by two guides, two mules (one named 9-1-1), and a dog we called Snoopy. Shortly into the hike, our bodies, accustomed to breathing basically at sea level in Philadelphia's western suburbs, began to feel the effects of the ever-decreasing oxygen. Mentally, we fought the fear that we would succumb to altitude sickness. Four hours after we started, we were able to relax. We had made it to the lodge.

Day two of the tour would turn out to be the easiest physically. Our four-hour hike ended at a glacial lake, an elevation change of 1,155 feet. During the hike, we spotted 12 condors flying above the mountains. The festivities at the lake included a waist-high wade into some very cold water and a traditional ritual ceremony led by a local shaman. Sleep was uneasy that night, as we had been warned that the next day would be the hardest hiking day of the tour - an early-morning, 31/2-hour trek up a steep incline to a peak of 15,213 feet at the Salkantay Pass, followed by a 4-mile descent. By midday, we would be almost 4,600 feet higher than we had been less than 48 hours earlier.

The mountain scenery along the route included glaciers, snow-capped mountains, giant granite fields, and rushing streams. We tried mental distractions: Count your steps in groups of 100; look for unique rocks on the path; try to match the footsteps of the hiker in front. Finally, after what seemed like an eternity, we saw a sign that marked the summit. We had made it! Although breathing was difficult, we stopped to take numerous pictures at the top of the mountain pass.

On day six, we toured Machu Picchu. This turned out to be everything we expected: fantastic architecture, amazing buildings, and the living ruins of a long-dead culture.

On the ninth day, we arrived home about 2 p.m., three flights and 23 hours after leaving Peru.

Mentally and spiritually, this trip reaffirmed one of life's great lessons: We are always stronger than we think ourselves to be. Never understimate the power of positive thinking and of your spirit.