Earlier quoted context omitted.
No, although I've done many days of more than 18 miles in the mountains, including 50 mile single-day mountain races. (The elite runners complete those in around 6 to 7 hours, over terrain of similar difficulty to Colorado Trail.) I don't mean to downplay their achievement, but the article is about a pair of average thru-hikers, out for a relatively short thru-hike. It is something that the average person can do, if…
btw @hsitz I ask this question not to be rude, but to work out if overconfidence is driving the answer cf: ~ https://news.ycombinator.com/item?id=13620745
Yes, some people are overconfident. I would suggest that the main problem in the context of endurance activities, though, is that people tend to be underconfident. People never get started because they think they can't do it, or that it would be too hard for them. They hear about people doing something like a thru-hike and they think these people must be gifted, special, or athletic in some way that they aren't.
That thought is almost entirely misguided. Certainly everyone has different abilities. But the vast majority of people out there doing these things have fairly average physical abilities. (For perspective, 2,000+ mile thru-hikes have been completed by children under 10 and people over 80.) They do probably have more motivation and dedication than most people, which are by far bigger determinants of success in these kinds of endurance endeavors than physical ability. But part of getting this motivation and commitment hinges on believing that they have the physical ability to do it (and/or that they can build themselves into physical shape to do it). Hence my post.
BTW, this is pretty much borne out by the guy who wrote the original article we're talking about. He didn't claim to be in great physical shape or have special physical ability, saying:
"Before the hike, I was fit but not training for anything. I ran five miles a couple times a week, went mountain biking about once a week, and periodically lifted weights. Like most Americans, much of my day was spent in front of a computer. I was 35 years old, 5'9" tall, and 150 pounds, with a BMI of 22.2 and body fat composition of about 13 percent."