Edit (much later - time for bed, in fact): I watched it, favorited it on Youtube and posted the link on Facebook. [Wait. Will that embed it here? Oh, no it won't. Good. You know, on the old preview page, you could click the links to see if they worked.]
For two and a half minutes of this video, you get to watch all these young, good-lookin' people. Then there's big, fat, old Al. I dragged that lard-a** for 31 miles over some of the gawd-awfulest [two l's? ...Naw.] hills known to man. It won't surprise you that each circuit took me a half-hour longer to complete than it's predecessor. The first took 1:52. [Error Alert!! That was what the gal linked in the post below did. I was there at 1:58.] You're welcome to do the addition after that. It comes out pretty close.
I only face-planted once (landed in sand, so no big), tripped on a few roots (but caught myself) and had my feet slip out from under me in the big ditch-y thing coming down the final slope before finishing. That fall didn't hurt... but getting up again did.
Going down hills like that? Every bit as tough as going up them. I mean, unless you're actually suicidal.