I didn't know it was possible either until the day came when, well, when I was tricked into it. Not really that someone fed me false information, or even that the trick was contemplated and played out with great accuracy. I actually like to think that nature dealt me this trick as a little shove into the outer boundaries of hard core I didn't know I had.
It actually came as a plan B. Originally me and a group of friends had intended on going to Havasupai for a few days but in the last mile of the 10 hour drive we were stopped by two Indians who told us it was closed because of swine flu. Not that THEY had swine flu, but that they thought WE had swine flu. So, we needed another plan and the grand canyon passed as the place to go.
Before this little rendezvous, I didn't even know a decent to the VERY bottom of the grand canyon was possible unless you were a Buffalo Bill or a Jim Bridger type of character, but alas you can do it as a not so notable figure like Bryan Brown. And we did it in 9 hours. It was a 6,000 foot decent, 16 1/2 miles and in the middle of the day. It was hard, but so worth it. I'm not doing it again though.
Disclaimer on the picture....this was BEFORE we did the hike. I guarantee we did not look that pleased afterwords.