Zac Efron, Jeremy Allen White, Harris Dickinson & Stanley Simons are sharing secrets from "The Iron Claw" set. The foursome caught up with Access Hollywood and joked about needing Zac's workout routine. "I still want it written out, like I want to know exactly what happened because you look amazing. It's so crazy," Jeremy joked to his co-star. The actor's team up to portray the true story of four of the six Von Erich brothers, one of wrestling's most famous dynasties, in the film, and shared how they became close while training together. Zac also reacted to Stanley serenading him and the cast with his own rendition of the "High School Musical" hit, "Breaking Free." "It was pretty great!" Zac admitted. "We were talking it all pretty serious when we were in there so to have a moment of levity was really fun." "The Iron Claw" hits theaters Dec. 22.