He said: "I held off and held off doing the audition because I couldn't find a way into the character. And when I finally did I went for it.
"I got a half a day of acting with 'Casino Royale' director Martin Campbell. I got to do some scenes with some great actors, gave it my all, and it wasn't right for me."
However, the experience led Sam to believe in his abilities, which helped him land the lead role of Jake Scully in James Cameron's 'Avatar'.
He told ShortList magazine: "I was backing myself. I had nothing to lose and everything to gain.
"I thought the least I'll get out of this is to act a few scenes with James Cameron, and that's a hell of an opportunity.
"I learned that from going for the James Bond audition. If I give it all I've got and still don't get the part, then so be it. This time I did."
Sam will soon appear in cinema screens again - his action adventure movie 'Clash of the Titans' hits theatres in April.