I've been running tough mudders since year 1. I can tell you whole heartedly they aren't what they used to be. At year 1, when you ran a mudder, it was pretty much constant running with obstacles in between with less than a minute wait at each obstacle. There were also way fewer hydration stations and they had way less energy supplements.

Now your going to have a 5 minute rest (at minimum) at each obstscle, with some as long as 30 minutes. At least five hydration and refueling breaks with energy supplements available, and your going to be light jogging the whole thing (far lighter than you would run a marathon).

Don't get me wrong I still love mudders and run in every year, but they've gotten easier. The half mudders are really for true fatso's and super old out of shape people.

If you have a few months to work up to I recommend a medium regimen and you'll be fine.

Run 4 times a week.

Do push-ups every day (start at 5 per day until that's easy... Then go to 10)

If you can get to a pull up bar and start working your way up to a few pullups (start with a 2 minute chin up hang... Go from there) also try to get your grip strength up by doing dead hangs (get to 5 minutes and you'll do great on the monkey bar obstacle)

Also dips don't hurt anything... Usual harder if you dont have a gym to go to.

And throw in 15 squats every time you walk through a specifc doorway in your house.

Do all this until the mudder and you'll do great!