Daniel Craig's ''vanity kicked in'' when he realised he had to strip for 'Skyfall'.
The muscle-bound actor reprises his role as super spy James Bond for the film and he worked out up to seven hours a day for the movie, because he wanted to look good on screen.
He told UK TV show 'Lorraine': ''There's stuff in the script that says I have to take my shirt off so vanity kicks in and I work out.
''But also I'm running most of the time during this film - he doesn't really just walk into a room and sit down, he tends to jump through the window and sit down, so I had to stay in shape.''
The 44-year-old actor's co-star Naomie Harris previously revealed she enjoyed filming the scenes with him when he had to take off his clothes.
The Bond girl said: ''I do get to have a lovely moment with him, where I try to seduce him. He's a very hot guy, definitely. He worked out for two hours every day after filming.
''He's a Bond in real life - very physical, capable and energetic.''
Daniel also said he is now extremely comfortable in his role as 007 now he is on his third film as the iconic character.
He explained: ''I think it's about time, really, isn't it that I should start feeling comfortable? I enjoyed this a great deal and like I said about the script, when you've got something as strong as that, and when you know the story is that good, you feel good about it. I always wanted to start bringing in the older elements of the films.''
'Skyfall' - which was directed by Sam Mendes - will have its Royal world premiere tonight (23.10.12) at the Royal Albert Hall in London.