5K training is one thing, but what if you throw a chest-deep pit of mud into the mix? Or a 9-foot-high wall? Or a line of actual fire to leap over? These are all common features of the mud run, one of the messiest running events out there. But who would sign up for such a dirty (not to mention, strenuous) undertaking? As it turns out, a lot of people; mud runs are some of the most popular amateur “fun runs” out there.

You might think it impossible to prepare for this kind of obstacle course without digging a trench through your neighbor’s tulip bed, but you really can do most of your mud run training at your local gym. We’ve compiled some training tips from Rob Dickens, organizer of Rugged Maniac mud runs. With events in 18 states plus Canada, Rob has plenty of experience in preparing for more unconventional courses, a process he says isn’t as daunting as you think.

First Things, First: Perfect Your 5K Training

Obstacles or no, a mud run is still a simple foot race at heart. “If you want to get the fastest time, focus on running,” Rob says. “Most winners are actually former long-distance runners.” If you’re already used to 5Ks, then you should rest assured that you’ll be A-OK on race day. If you’re new to the sport, however, it’s important to work up to running 3 miles at a time.

Interval training—alternating periods of intense exertion (running) with periods of rest (walking)—is a great way to start. Be sure to gradually decrease the amount of time you walk until you’re able to hit that 3-mile mark without stopping. Free apps like Couch to 5K can help you map out a training program with ease.

Build Up Your Quads

“You’re jumping, crawling, sliding, running, and tackling a host of obstacles that are both fun and physically challenging,” Rob says, which is why your quad strength is important. In addition to leaping over obstacles and fighting your way up steep (often muddy) hills, your mud run might even include trampolines. “It looks pretty easy, but most people struggle to bend their knees at the right time and end up flailing around . . . until they figure it out.”

To prepare yourself for all that jumping, the dreaded burpee workout is your best friend. Since they simultaneously work your quads and core (plus your hamstrings and calves), fitting burpees into your mud-run training can help keep you on your feet.

Incorporate Arm Workouts Into Your Running Routine

“You have to use ALL of your body, not just your legs,” Rob points out. With obstacles like Rugged Maniac’s “The Ringer, which is a series of ring-shaped handholds suspended over water,” or the 9- and 10-foot-high walls that are a staple of many mud runs, a good grip and strong arms are important. Rob suggests breaking up your running routine with standard pushups and pull-ups to build muscle.

Don’t Forget to Mentally Prepare

As physically demanding as a mud run can be, there’s an equally strong potential for psychological exhaustion. Maybe your pulse starts racing when you eye the 50-foot slide or your palms start sweating as you near the confined space of the tunnel crawl. Everyday fears can really hinder your performance on the course!

If you’re feeling uneasy about these or any other obstacles, it’s important to remember that it’s perfectly acceptable to skip them. You don’t even have to run if you don’t want to—it’s all about fun. “If you just want to come out and experience the obstacles and party in the festival, you don’t really have to train at all!”

Guess you’re off the hook for those burpees, then.