While in the Galapagos, we hiked up the side of the Sierra Negra Volcano on Isabela island. Our guide, clearly accustomed to the altitude and physicality, expected us to hike up and back down in the time it took most to make it to the top.

The angle was steep, the terrain rocky and we battled a hot sun with little shade or breeze. I had a particularly rough hike, suffering from a mixture of heat exhaustion, altitude sickness and an increased asthma-induced heart rate. Pausing frequently, the gap between us and the group grew wider, but we did not stop.

On the last stretch, I paused alone, resting on a cool patch of grass. My lungs calmed, but my vision blurred, and I started to sway. Terrified of collapsing, I quickly arose to climb those last few steps to the edg...

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