Ben Rothstein/Twentieth Century Fox

The 'Scorch Trials' Cast On Why 'Freak Athlete' Dylan O'Brien Rules At Stunts

Cardio on fleek.

When the Gladers escaped the titular maze at the end of "The Maze Runner" last year, they (and we) probably never thought that they'd have even more, far more difficult running in store. But that's exactly what's going to happen once Thomas (Dylan O'Brien) and company hit the "Scorch Trials" -- and the cast (and their glutes and hammies) are feeling the pain.

"I didn't think it would be more running, but it is, funny enough," O'Brien told MTV News when we visited the film's Albuquerque set. "It's running everywhere; it's running away from things, up sand dunes."

These sand dunes -- which were poured all over the abandoned mall that the cast was filming in during our time on set -- became a huge physical challenge for the cast, who Kaya Scodelario rightfully said were hired because they look more like normal, in-average-shape teens than superheroes. But lucky for them, they had seasoned cardio vets like O'Brien and Ki-Hong Lee to look up to.

"The sand just makes you stand still," Scodelario said. "You're like a cartoon. Your legs just move, but your body doesn't. You just sink lower and lower into it. I'm the worst, I'm the laziest by far, I don't like exercising at all, and they kind of push me to do it. I look at Dylan and Ki-Hong and think, 'If they can do it, I can do it, too.'"

Scodelario wasn't the only one who looked up to Lee or O'Brien when it came to grueling stunts -- Dexter Darden, who spent a lot of time sitting pretty as the cook Frypan in the first film, pointed out that pretty much everybody looked to the athletic O'Brien for leadership.

"Dylan is a freak athlete," Darden explained. "I don't know if people know that, but Dylan is really, really fast, and he's really talented at baseball. Ki-Hong is really fast, too... it was kind of easy for me to jump into the running, but I think we were all in the same boat when it came to Albuquerque. Dealing with this altitude, this is something that none of us have ever seen before. We definitely kind of ride Dylan and Ki-Hong's coattails a little bit, just from knowing how to run and how to look cool running."

Does anyone look cool running? Either way, O'Brien concluded that running your ass off, in the "Maze Runner" universe, is all part of the fun.

"All that's a part of it," he said. "It's just fun. I wouldn't have it any other way."

"The Maze Runner: The Scorch Trials" hits theaters on September 18.