For those who have never seen the show American Ninja Warrior: Imagine an Army obstacle course, redesigned by Dr. Seuss and a team of rock-climbing acrobats. Competitors have to thread their way through the daunting obstacles, completing a number of stages before they can hope to finish the whole thing.

That means leaping onto 2-inch ledges, climbing rope that stretches several stories in the air, grappling forward along hanging poles — and doing all of it under a time limit.

Since the show (based on a long-running Japanese show, Sasuke) first aired in 2009, not a single person has completed the course and won the American competition … until last week.

A busboy named Isaac Caldiero — who also happens to be a world-class rock climber — became the first of thousands to achieve what the show calls “total victory.” He completed all four stages of the course to win the million-dollar grand prize.

In fact, two people completed all four stages this season: competitor Geoff Britten finished the course first. But Caldiero had a faster time, and won the money — and the title.

In an interview with NPR’s Arun Rath, Caldiero puts it simply: “Heck, you’re talking to the first American Ninja Warrior.”

But it didn’t come easily, not least because competitors have to attack the course without getting to practice on it first, he says.

“I mean, all it takes is one slip and you’re done. One shot, one kill — you don’t get any rehearsal on any of these obstacles.”

This made things especially difficult on his final obstacle: a 75-foot rope climb.

“Even in my training, I had never done anything like that,” he says. “So all of a sudden, when it’s like, ‘You have to do this in 30 seconds,’ I was very nervous. I was like, ‘Oh my gosh, here we go.’ “

Yet, despite a brief scare as his arms slowed, Caldiero says his adrenaline carried him through. Now, though, he faces another difficult task: letting the news of his win sink in.

“It still to this day is unreal,” he says. “I’m still kind of in disbelief.”

And about that million-dollar prize?

“We considered ourselves to be rich and happy before all of this, so this is just a bonus,” Caldiero tells Rath, speaking of himself and his girlfriend, Laura Kisana. “You definitely aren’t going to see us out driving around in fancy cars and living it up. You know, we’re going to keep down to our roots, and we’re going to go rock climbing.”