The actor said he had to get into top shape for the film -- especially since in one scene, he's doing several one-arm pull-ups effortlessly. Wahlberg, 44, told E! News that when he filmed that scene he "did probably about 700 that day."
"We did many takes from many angles," he added.
Wahlberg admitted to having a little movie magic help him with his onscreen workout. A "gentleman underneath" provided support for him, he said.
"They didn't want me to sound like I was giving an effort whatsoever," Wahlberg explained, "so I'm talking very calmly during the push-ups and then the pull-ups."
Ferrell said it's one of the most memorable scenes in the film. "I think it's the funniest scene that Mark doesn't break a sweat," he continued. "We're just having this very civil conversation while Mark goes through this intense workout."
Wahlberg said he had to get into "great shape" to portray his character, Dusty.
"We were shooting right around the holidays, which is when I really love to splurge. So I wasn't able to drink anything or eat anything other than a strict diet," he explained.