Muddy Buddy - Not just a delicious treat

So Husband recently proposed that we participate in an outdoor activity known as the Muddy Buddy while subsequently holding up a shiny object which I was, of course, fixated on resulting in me not paying any attention to what he was saying. This Muddy Buddy consists of a 6-7 mile course that you run/ride with a partner. From what I can understand, both members of the team start out at the same time, one running and one riding for 1 mile at a time. Then you go through an obstacle course and switch positions so that you're alternatively running and riding until the end where there is a huge mud pit that you have to crawl through. Somehow, I agreed to participate in this activity even though running to me is equivalent to what Dante describes as the second circle of Hell. Everyone I talk to about this has said, "Oh you can do that, it's only 3 miles of running." To me, that's like saying stripping is easy for a one-legged woman (although I have heard of this mythical creature at a certain "Gentleman's Club" in Waco). What I don't understand is how people actually like this thing called running but people have been swearing by it for years. So Husband and I started our new "training" program last week which I will say has been painful but bearable. Wish me luck.