Matt Damon and Ben Affleck didn't "know what [they] were doing" when they wrote 'Good Will Hunting'

Matt - whose friendship with Ben goes back to their school days - shared: "I think 'Good Will Hunting' took us so long, we were like unemployed broke guys. It took us forever to write that screenplay.

"I think we wrote thousands and thousands of pages, we didn't really know what we were doing. I think that put us off writing again, because we never thought we'd have the time."

Matt and Ben reminisced about writing the much-loved movie during an appearance on 'The Tonight Show Starring Jimmy Fallon'.

And Matt admits that their writing speed has increased dramatically over the last 25 years.

The actor - who co-wrote the new historical drama 'The Last Duel' with Ben - added: "We found writing this that we actually picked up structure over the last 25 years of making movies, and so it went a lot faster."

And after they were both shown a photo of them together at the 'Good Will Hunting' premiere, Ben quipped: "You wouldn't image that those two idiots would still be around!"

Ben also admitted to being shocked by the success of the movie.

He said: "We were just shocked that it all happened and wouldn't have imagined getting another job. The whole thing of 'Good Will Hunting' was really just to make them a video cassette that was like an acting reel."

Matt and Ben have reunited to write and star in 'The Last Duel'.

But Matt recently admitted he didn't think they'd ever "find the time" to collaborate again.

He explained: "[We] assumed [writing] would be so time consuming that we'd never be able to do it."