I'll speak up for the non-athletes.
As a kid I participated in a handful of March of Dimes walkathons, which were 20 miles on city streets. Took most of the day.
Then in the early 80s I completed a half-marathon, which is 13.1 miles.
The longest trail hike (with light backpack) I've done is about 9 miles, not that much, but I did it essentially three times in four days. That was a big deal for me.
Day 1, trailhead down to Havasupai village, 8-9 miles w/light pack.
Day 2, about 8 miles dayhike with minimal pack.
Day 3, rest (freeze dried thanksgiving dinner celebrated on an Indian Reservation, that's the way to do it!),
Day 4, 8-9 mile hike back up/out to trailhead with pack.
Not as big an effort as some of youse guys who are serious endurance types, but at least I don't have to say that "2 miles to a picnic" is as far as I've gone...

"... among the ways available in which a man can die, it is a rare and signal distinction to be killed by a leopard."
-- Raymond Dasmann