You never forget your first SMMF, or Single-Movement Mind F*ck.

It’s exactly what it sounds like—one exercise repeated over and over and over again until you finish, quit, or go bat shit crazy. It puts you in a state of serious physical and psychological stress. But if you finish strong, it’ll forever change the way you work out.

My first SMMF was on New Year’s Day of 2009. I was visiting family in Canada. All of the gyms were closed and my mom had no fitness equipment in the house. (For 3 intense workouts that require zero equipment, check out Bodyweight Cardio Burners.)

So I went into the laundry room, which was the only unoccupied room in her house and just big enough to fit the washer, the dryer, and me.

Then I did 2,009 lunges.

It was the definition of terrible. My legs burned. My body shook. My mind went hazy. It felt like torture, and there were multiple moments that I wanted to throw in the towel. I kept going, though, until I finished the last rep two hours later.

That’s why you’ll find SMMFs pop up occasionally in training plans at Gym Jones. They build an unparalleled work ethic, while teaching extreme perseverance and mental strength. And best of all: SMMFs reset your perspective. Ultimately, they make you better in and out of the gym.

Below are three of my favorite SMMFs. Try them, and learn just how far you can take your body and mind.

One-Rep Marathon Whether you’re doing 5 sets of 20 reps, 20 sets of 5, or 10 sets of 10, 100 reps of an exercise a lot of work. However, doing 100 sets of 1 rep at a time is a entirely different animal. This one is a head trip.

Lunge to Nowhere This one is straightforward: Do 1,000 lunges, 500 on each leg.

There’s one small catch, though: These have to be standing lunges, not walking lunges. Why? Lunging from point A to point B—like around a track—is easier because the distance you’ve covered serves as motivation.

One thousand lunges in-place can make you unhinged. The first 50 and the last 50 aren’t bad. But those 900 in the middle are no man’s land. Only the mentally tough survive.

Want to make this even harder? Do it facing a wall, in silence. Or just do 2,009 reps.

Grab two 24-kilogram kettlebells (or a pair of 70-pound dumbbells). Hold one in each hand. Now walk for one mile. (You can set the weights down and rest when needed.)

This is best done in a gym. Measure the distance across the gym in feet, then divide that number by 5,280. That’s how many times you have to walk across the gym. God speed.