September 30. I need to write all of this down in a longer piece. Just noting here: It was the most exhausting thing I’ve ever done.

Got up at quarter past four, left at quarter past six at sunrise at the South Kaibab Trailhead. When we got to the red zone inside the canyon four hours later, I collapsed just before Phantom Ranch with some kind of heat exhaustion and was pretty scared I’d never get out of there unless by helicopter. Ed, the biologist who studies fish in the canyon and happened to come along the way, took matters into his own hands and made sure I recovered, including bathing in a crystal clear bubbling stream, delightful conditions to be exact.

Set off again three and a half hours later, in a state that was actually already exhaustion. Often thought of the signs at the start of the trails: Down is Optional, Up is Mandatory. Two-thirds of the way – the hard two-thirds – were still ahead of us.

There was never any doubt that I would make it, the only question would be how long it would take, and how sore my feet would be, and how heavy the backpack would feel when I put it down, and how dreadful it would be to put it back on. Never a doubt? Just as I didn’t know what heat exhaustion felt like before that day, and that it could happen to me, I don’t know when I’ll collapse from exhaustion – because it’s equally clear that I would eventually – and what that feels like.

The distance between me and my son has grown significantly over the past five years. It’s not – he explains to me – that my lungs are getting weaker, because they’re well trained, but that my circulation is getting worse. The arteries are calcifying, and there’s ultimately nothing you can do about it. So I work my way up with an old man’s breathing that sounds unnecessarily shallow and always a bit panicky. I sometimes spend too little energy silencing the sounds of my efforts, my groans, and I’m ashamed of it in front of my son. But most of all, what matters now is making it to the top. When he stops to look at an animal, a special view, I just want to keep my steady rhythm.

Cooled our feet in the water at Indian Garden. Four and a half miles to go, the hardest of all. Three quarters of an hour after we left, the sun sets. From the Three-Mile Resthouse, we need the headlamps. This is not an emergency. There are dozens who complete or even begin their hike in the dark. But we are as if placed into another world, one that consists only of the small white circle of light in front of our feet. In it, sometimes, bugs. Scorpions. Spiders. For two hours we work our way forward like this in the dark, without any orientation except for the mileage on the smartwatch, which grows incredibly slowly.

We also don’t see the Rim ahead of us, that sight that makes the last few meters easier during the day. For an hour we can’t believe it’s still not over. At nine we arrive.