Love watching American Ninja Warrior and toying with the idea of trying out?

Well, let’s just say it’s really, really, really...really hard.

Just ask pro rock climber Isaac Caldiero, 35, of Utah, the first-ever American Ninja Warrior participant to win its $1 million prize. After a few years of trying out for the show, he finally perfected his training by building replicas of the obstacles in a compound in his parents’ backyard.

“I specifically designed them so I could go from one to the next, back-to-back, 'till failure,” he says. “I got to the point where I could do all 13 of them in a row. And I’d just do laps over and over.”

Caldiero offset his obstacle prep with free-solo climbing—basically rock climbing anywhere from 30 to 100 to 1,000 feet off the ground—plus lots of trail running.

Karsten Williams, a 36-year-old personal trainer from Plano, TX, who’s competing on the show for the fourth time this summer, took a slightly different path.

“I thought I was prepared, but it turned out I wasn’t,” he says, recalling how he fell on a really easy obstacle, the Quintuple Steps, in his first season—one of his most humbling experiences, he says.

So he traveled from Dallas to Houston to work out at an obstacle gym, and focused less on weights and more on bodyweight training to build agility. He used the monkey bars and other equipment at the park to simulate the course obstacles.

What would these guys advise you to do to become Ninja Warrior material?

“I’d start with sets of 10 pullups with one-minute rests in between, and do that 'till I could do a total of 100,” says Caldiero. “And during each rest, try to do 10 pushups.”

Williams’ advice: “You should be able to do at least 15 full-range pullups, hang on a bar for at least 45 to 60 seconds, and knock out a good 50 pushups in one sitting. That’s a good baseline for the strength and grip requirements.”

Do that—and work on balance, flexibility, and speed—and you might have a shot at the show.