The actor recalled that he was "really irritated" by critics who thought that he was "slumming" in the role because of his previous theatre work, The Times reports.
Stewart said: "One day I lost control and I said 'Listen, not only am I proud and delighted to be playing the captain of the Enterprise, but all those years working for the Royal Shakespeare Company…sitting in the throne of England, was nothing but a preparation for sitting in the Captain's chair on the Enterprise'.
"I'm very proud of that work, very proud of it. We had a lot of fun but we took the work itself very seriously. We always tried to make it sound intelligent, thoughtful and significant."
He also told interviewer Clive James that there was "something quite classical" in Star Trek dialogue and that the show had a "quality about it".
Stewart will reunite with former Next Generation stars including Gates McFadden and Brent Spiner in an upcoming episode of animated comedy Family Guy.