The Massachusetts-born comedian officially takes over for Jay Leno starting Monday.
"I think the biggest danger to me taking over 'The Tonight Show' -- and I've thought this since the beginning -- is over think," O'Brien told The Boston Globe.
The comedian, who is no stranger to late-night television thanks to NBC's "Late Night with Conan O'Brien," also recognizes how important it is for him to follow the TV legacy set by Leno and previous "Tonight Show" hosts Johnny Carson, Steve Allen and Jack Paar.
But O'Brien added the TV show's pedigree will not stop him from embracing the sillier portion of his trademark humor, the Globe reported Sunday.
"It's a venerated, beloved NBC franchise," O'Brien said of the show, which averages nearly 5 million viewers a night. "That doesn't mean I can't do silly things in that space, but the space itself should be beautiful."