YouTuber and calisthenics athlete Stan Browney regularly faces fitness challenges that push him to his physical limits, including trying to lift a total of 100,000 pounds in a single hourand try to train for 24 hours straight. In his most recent video, Browney decides to try running the “world’s toughest marathon”: in other words, running a mile every hour for 24 hours.

“I have no running experience and no idea if I’m going to die in the next 24 hours,” he says.

Browney is joined in the challenge by friend and fellow fitness influencer Arjen Albers, who points out that they don’t have the best running technique for this type of endurance event.

They run the first mile in 6:43, then experiment throughout the day with faster and slower paces, to find the right “flow” they can follow when running all night – but they quickly realize that they hit a 5 minute mile was a mistake, as it increases their fatigue and need for recovery.

The physical toll of the hourly races becomes evident on day two, with Browney pushing through pain and bleeding feet and Albers struggling with the limited amount of sleep they get between miles.

“I’m just tearing my body apart,” Browney says. “It’s not good for my body.”

After covering 24 miles in 24 hours, Browney insists they keep going: if they can manage another 2.2 miles, it will take them to 26.2 miles: the official length of a marathon.

“The only thing I’ll say about this challenge is don’t try this at home,” an exhausted Browney said at the finish line. “We don’t encourage doing that. We’re dead.”