Michael B. Jordan found staying in shape for 'Creed' "really, really hard".
Jordan began his preparations to play boxer Adonis Johnson Creed over a year before filming started and admits sticking to a strict diet regime was tough.
He said: "To walk around in that shape is really, really hard, especially with the schedule of life in general.
"It's probably one of the hardest things I've had to do. I ate clean - no sodas, no junk food.
"You have your cheat day and eat whatever the f**k you want, but the next day you feel it and it kind of tell you that you don't want it."
Michael had to train as a "real fighter" but admits screen boxing is very different to practicing the sport in real life.
He told heat magazine: "I had a trainer who was there smacking s**t out of my hand for the first week and a half until I got used to it.
"During pre-production, I trained as a real fighter.
"In the movie, you have to over-exaggerate or telegraph the moves, in a slo-mo shot or something.
"You go into movie boxing mode - it's 'moxing'. Know what I'm saying?"