Let's just say "fun" isn't exactly the right word to describe Josh Brolin's experience on "Oldboy."

Not only did the Oscar-nominated actor have to gain and lose massive amounts of weight in short periods of time for the remake of Chan-wook Park's cult 2003 thriller ("that's just not okay for your body," he conceded), he also suffered mightily when it came time to film a ramped-up version of the legendary single-take brawl from the original movie.

"It [was] much more painful than it should have been, you know?" said Brolin of filming the scene, which unlike Park's version takes place on multiple levels. "Our version...was probably four times as long as the original. But it was what it was, they set it up and we thought it was good. I didn't know if I could pull it off or not during most of rehearsals. And then the two days that we did it, there were a lot of tears at the end of it. Painful tears, and just grateful tears."

To hear what else Brolin had to say about the physical demands of the role, what it was like to work with director Spike Lee and why he sought out Park's blessing before signing on for the film, check out the full interview above.

"Oldboy" hits theaters on November 27.