Pain & Gain: Mark Wahlberg & Dwayne Johnson Talk Bulking Up For Action Movie

Access Hollywood
Mark Wahlberg and Dwayne 'The Rock' Johnson are sighted on the set of 'Pain And Gain' on April 4, 2012 in Miami -- Getty Premium

Mark Wahlberg and Dwayne Johnson had to kick their fitness up a notch for the upcoming bodybuilding movie, "Pain & Gain."

While both stars amped up their physiques for the Michael Bay-directed flick, Mark said he had to work hard.

"I had a huge preparation," Mark told Access Hollywood at the "Pain & Gain" premiere in Miami on Thursday. "And then also just letting loose, becoming this character. I was always fascinated with the world of bodybuilding."

PHOTOS: Mark Wahlberg

Mark's kids were divided on their dad's new look.

"My daughters didn't like it. My sons absolutely loved it," he said.

PHOTOS: Best Beach Bods - The Men

Mark's ripped bod will come in handy for his next film (also with Michael Bay), "Transformers 4."

"We start [filming] in a couple of weeks," he said. "I'm ready to go."

PHOTOS: Solid As A Rock! Dwayne Johnson

As for Dwayne, "The Rock" didn't have to undergo as much of a physical transformation for the film.

"I was really fortunate because I was coming off of 'G.I. Joe,' I was coming off of 'Fast & Furious' at that time too," he explained, referencing his recent films. "So a lot of those projects supported and fostered the type of training I was doing."

Adding, "The biggest thing with a movie like this -- the biggest departure was the vulnerability and showing this type of vulnerability, and playing a character who is easily influenced and who's just out of prison and looking for salvation."

"Pain & Gain" hits theaters on April 26.

-- Erin O'Sullivan

Copyright 2013 by NBC Universal, Inc. All rights reserved.
This material may not be published, broadcast, rewritten or redistributed.