Alex Honnold

I was 19 when my father died from a heart attack. He was a 55-year-old college professor and had led what was by all appearances a risk-free life. But he was overweight, and heart disease runs in our family.

I've done routes where I've climbed 200 feet off the ground and just been, like, 'What am I doing?' I then just climbed back down and went home. Discretion is the better part of valor. Some days are just not your day. That's the big thing with free soloing: when to call it.

In the years after the expedition to Chad, I started the Honnold Foundation, a small nonprofit that was my attempt to do something positive in the world. I sought out projects that both helped the environment and improved peoples' standards of living. The more I researched, the more I gravitated toward solar.

I was 19 when my father died from a heart attack. He was a 55-year-old college professor and had led what was by all appearances a risk-free life. But he was overweight, and heart disease runs in our family.