I did the WI Tough Mudder last year, and took it quite seriously. Upped my trail running, made sure my gear worked when wet, tapered and carb-loaded before the run. I think I mostly did it because I didn't quite know what to expect, and I was intimidated by what I heard and read. On game day, everything came together perfectly, I had an 8am start time, the weather was perfect, and I was pretty much in peak condition. I ran solo, a bit apprehensive at first, but after the first few obstacles the tension fell off and I breezed through the course, with the exception of the greased quarterpipe, where it took me several tries until someone caught me. To my surprise, the time was good enough to earn me a qualifier for the World Toughest Mudder, which I did not use, however. I do know my limitations.