Even Harlan, who had achieved a level of mastery I still had trouble imagining, had been spit out the bottom of Lava, upside down, his paddle snapped in half and his nose almost broken. No. Humans were not the driving force, I thought. We were more like rocks in the river or the canyon walls, being scoured and eroded by circumstances and time. And I was powerless in the face of that energy.

But as those ideas and doubts flooded through my brain, there were persistent examples, a number of outliers, people who seemed to run counter to the theory. Rob was one of them. I remembered him on the Usumacinta, beaten down by the effects of cancer, his spine fractured, yet paddling furiously toward a drowning teammate and saving his life. His cancer had been a kind of challenge he’d never confronted before, yet, despite that, he bravely went forward to live fully and confront the uncertainty that lay ahead.

There were many other examples, too. To name just a few, there was my old friend Mark Wellman, who had broken his back yet had climbed El Capitan. He’d performed a kind of alchemy, turning lead into gold. Kyle Maynard had pioneered what seemed impossible and, with a great team around him, crabbed his way to the top of Kilimanjaro. Mandy Harvey had done something preposterous by learning to let go and write and sing music she would never hear.

It occurred to me that all these friends had something in common: Their actions were counterintuitive, defying the reality of what they saw and felt. They grew rather than diminished. They went in unlikely directions, instead of accepting safety and stagnation.

And Terry Fox was always at the top of my list. Despite all the evidence pointing toward futility, he had chosen to run thousands of miles across a continent. He would never live to witness the results of his heroic act, yet he had done it anyway, and that choice had made all the difference.

If my life had anything in common with a rapid, it made sense that there was a map, one that was even harder to read than the one on a river. These people had illuminated parts of that map, had lit up the path like contrails in the sky, like bioluminescence in dark water. It was a map I desperately yearned to build and follow. And the choices I made would either paralyze me, send me spiraling into a whirlpool, or propel me forward, admittedly in crazy and unexpected ways.

It was staggeringly difficult, however, not to see the overpowering evidence of the world, and use it as validation to protect yourself, and to shut down. It took such relentless trust in your team, in what lay ahead, to stay open to the possibilities that existed like a blank canvas, or like the infinite sky that gave promise to those features that could be touched, heard, and seen.