Guillermo del Toro originally signed up to take charge of The Lord of the Rings prequel in 2008, but he had to quit due to production delays when the studio behind the franchise, MGM, fell into financial turmoil.
Peter Jackson took over as director and the movie series eventually got back on track after the company emerged from bankruptcy, but a dispute with an actors' union and a health crisis for the filmmaker led to more postponements.
The first movie in the trilogy - The Hobbit: An Unexpected Journey - is finally due for release next month (Dec12) and McKellen has now revealed he considered walking away from his role as Gandalf on at least two occasions due to the delays.
He tells the December (12) issue of Reader's Digest, ""I thought more than twice about it. It begins to wear you down. You think, Do I really want to do this? (A friend of mine) said, 'Look, Ian, all the fans of Lord of the Rings want The Hobbit to be made, and they want you in it.' I thought, Yes, I've a responsibility beyond my own pleasure. So I had to clear 18 months (from my schedule). And at my age 18 months is quite a long time.""