Catherine Zeta-Jones is too lazy to exercise often.
The 'Rock of Ages' star loved getting the opportunity to start dancing again for her role in the musical bit admitted she slacks off exercising when she is not working.
She told S magazine: ''I haven't danced for a while. I work out and I have a ballet barre in my gym. But every time I do it I think, 'Why don't I do this all the time?'
''I get lazy so working on this film was a bit of a shock to the system. It was like 'OK, I remember those Achilles, I remember those thigh muscles'. All those elements came back and it worked out great.''
Catherine, 42 - who is married to screen legend Michael Douglas - also revealed she loved getting the chance to work Tom Cruise on the movie.
She said: ''He's awesome. But that doesn't surprise me. Tom throws himself into every role he does so fantastically well and it shows on film. That's why he's Tom Cruise. But to see him in this film is a real treat.''