Last summer my wife and I did the Hell Run and the Gladiator run. These things are all very similar and very fun. Don't worry about getting all buffer up for these, you don't have to run if you don't want to. It's not a race, you are just competing with yourself for the time. It is a social kind of thing, like a party, which they all have (beer garden) when you complete. I highly recommend doing any of these events just for fun and the unique challenge. (And don't be afraid to get muddy, that's the point. If you come to the end and you're not muddy, you wussed out.)