Has anyone ever done one of the "Tough Mudder" events? Some friends I work with talked me into signing up with them. It's next weekend in Pennsylvania. Apparently it's a course designed by British Special Forces - 11 miles with obstacles ranging from walls to swims through ice cold water to running through wires with 10,000 volts of electricity

It looks daunting, but at the same time it looks like a lot of fun. These types of events seem to be hugely popular these days. To stay in shape, I swim regularly. I've added some running on the treadmill to my regime, and some strength training too. I consider myself to be in decent shape, but if anyone has any first-hand experience, I'd appreciate any tips...
Thanks!