These sorts of events are popping up all over the place now. There are dozens of them.
Spartan Race
http://www.spartanrace.com/#.
Death Race
http://www.youmaydie.com/
Good luck in this one. A friend of mine did the Death Race last year in Vermont and finished, which is an accomplishment. It's not just physical, but mental as well, like you have to carry a tree stump around with you for hours, while doing other physical challenges, then run to the top of a mountain while still carrying the stump, and answer questions on US presidents. If you get one wrong, you have to go back down the mountain to a checkpoint then come back up and answer another set. Another one was at some point you get a card showing an assembled lego piece. After 24 hours of other physical pain and agony, you have to assemble the lego from the parts they give you, from memory, from seeing the card brieflty 24 hours ago. If you get it wrong, you get sent back. Kinda crazy. Not sure I see the point.
Forgot to mention - GOOD LUCK!