Chris Pratt starved himself for 'Guardians of the Galaxy'.

The 35-year-old actor stars as Peter Quill aka Star Lord in the upcoming adventure sci-fi and he's confessed he had to put a lot of hard work into making sure his body looked good on-screen.

Quizzed on whether he was someone who takes good care of himself, he laughed: ''No, I am not. That is ... For almost my entire life that has not been the case but for this movie I did have to take care of myself for a while but that's quickly going to go away.

''[How did you look so good on-screen?] There's some airbrushing and a lot of sit-ups and sort of starving yourself knowing that you had a shirtless scene coming up.''

The 'Parks and Recreation' star has also revealed that he was sceptical as to whether the film was going to be any good once all of the different elements were put together.

Speaking on the 'Late Show with David Letterman', he explained: ''I saw it for the first time about two weeks ago and with a movie like this where two of the characters are animated and every world has at least some element of CGI, I kind of didn't know whether it was going to be good or not.

''I remember having a hunch we were doing something special when we shot it a year ago but I walked into the theatre pretty nervous and I'd been having all these nightmares that I was going to hate the movie but I saw it for the first time two weeks ago and really, really loved it.''