When it comes to workouts, I hate surprises.

This personality trait puts me at a disadvantage at this weekend’s SEALFIT 20X Challenge—an all-day bootcamp put on by current and former Navy SEALs. After six months of training for the event, I will finally have a chance to test myself on Sunday. The 20X is about pushing your limits and learning to deal with adversity. Surprises—specifically, surprising challenges—are pretty much guaranteed.

For proof, look at SEALFIT’s website, where the 20X is described as “intense, experiential training,” designed to help you “gain mental toughness and a warrior’s non-quitting spirit.” That’s as much detail as you get.

Compared to marathons or other endurance events, which faithfully cover a predetermined and agreed-upon distance, 20X keeps participants totally in the dark. How many miles will I have to cover this weekend? I don’t know. How many Push-Ups will I do? Can’t say. How long will the whole thing last? It’s unclear.

There are, however, certain things that I know will happen. For example, it’s a sure bet that the event will start with what’s called a “breakout.” What this is, essentially, is really hard calisthenics—“Grinder PT,” as the SEALs call it—performed under distressful circumstances.

By “distressful circumstances,” I mean there will be very fit, very well-trained men barking orders and hosing us down with frigid water. It’s loud, it’s confusing, and it’s meant to weed out people who don’t want to be there. For participants like me, the goals are twofold: 1) don’t panic, and 2) try to keep up.

Personally, I find not panicking to be a lot easier when I’m not caught off guard. Things are more manageable when I’ve been there before. For that reason, I asked a couple of my colleagues at STACK to help me create a breakout-like experience in my back yard.

So on a recent morning, STACK’s executive video producer, Scott Stachiw, came to my house to run me through a series of PT drills. The routine was based on former SEAL Brad McLeod’s “No Excuses” Bodyweight Workout, which is full of Push-Ups, Air Squats, 8-Count Bodybuilders, Burpees and other lung-busting moves.

The author gets a blast of cold water from his colleague, Scott Stachiw (yellow), while STACK producer Brandon DuBose films.

Stachiw is a big guy with howitzers for arms and a booming radio voice, so he was the perfect person to play drill instructor. I didn’t know how to repay him for the favor, but his role—to blast me in the face with cold water for about 20 minutes—hopefully made the experience worthwhile for him.

Meanwhile, another STACK video producer, Brandon DuBose, filmed the whole workout. You can watch it in the video above (if you haven’t already).

From this training session, I learned the following:

• Hose water is COLD this time of year.

• Getting sprayed with cold water makes exercises at least seven times harder. No matter how ready you are for it, the water sends a jolt through your body, causing you to tense up. The extra tension drains your energy, making it more difficult to perform whatever exercise you’re supposed to be doing. So the training becomes a double drain on your body. You have to make a conscious effort to calm down.

• I wish I’d asked Scott to give me a few breaks. Man, we went at a back-to-back-to-back pace at first, and I felt thrashed pretty quickly. But then, it’s unlikely the SEALFIT trainers will give us any breaks, either.

• At a certain point in the routine, you have to go on pure will. You know you’re moving slowly. You know your form sucks. But as long as no one is telling you that you’re slow, sucking badly and should drop out, you can keep going. Somewhere there’s a pace that will make it possible for you to complete the challenge.

So now I know what at least one part of Sunday’s event will feel like. The other 12 to 14 hours remain a mystery.

I’m ready for it. But still: Wish me luck.

Related Posts: 

SURVIVING SEALFIT, part 1: What Happened When a Regular Guy Tried to Train Like a Navy SEAL

SURVIVING SEALFIT, part 2: 3 Ways SEAL-Style Workouts Change Your Life

SURVIVING SEALFIT, part 3: The World’s Hardest Workout Has a Ridiculous Name

SURVIVING SEALFIT, part 4: Inside the Devil’s Backpack: The Only 5 Things You Need to Get A Hellishly Hard Workout Anywhere

SURVIVING SEALFIT, part 5: How Not to Hurt Yourself (Like I Did)

SURVIVING SEALFIT, part 6: Finding the Silver Lining

SURVIVING SEALFIT, part 7: The Question That Tells You Whether You’ll Succeed

SURVIVING SEALFIT, part 8: Meet 3 Guys Who Might Kill Me

SURVIVING SEALFIT, part 9: The Dress Rehearsal

SURVIVING SEALFIT, part 10: What a SEALFIT 20X Challenge is REALLY Like

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STACK Executive Editor Brian Sabin finds it hard to believe that six months have passed by so quickly, and that the SEALFIT 20X Challenge he’s been preparing for is finally here. It’s go time, folks. This weekend we’ll find out whether his quest to reach elite military-grade fitness was successful. Sometime next week, he’ll give you the full report on the event—the good, the bad, and the ugly. Between now and then, you’ll find progress updates on Twitter and Google Plus.