Krasinski's double dates with Damon
"My wife had worked with him on Adjustment Bureau, so we became friendly and did double dating," he explained from the red carpet of the film's Los Angeles premiere.
"And on one double date he said, 'I'm thinking of directing, and is there anything that you're working on that you want to bring to me?' and I said, 'Yeah', and this is the idea I brought him."
While Matt eventually decided against directing Promised Land himself, he called on his Good Will Hunting director Gus Van Sant to take the reins on the project.
"It just started out Matt and I writing, which was surreal enough, to be working with the guy who wrote Good Will Hunting," John said. "And then by the time Gus came on I was being surrounded by so many amazing people that we were really all in it together."
Matt revealed he had never been happier than he was when working on the script.
"It was fun to write the scenes too, we had a lot of laughs while we did it and I actually forgot how much I love writing," he said.
"My wife said in the middle of the whole process, 'Even if you never make this thing, I've never seen you so happy', so it was pretty great."