Krasinski invited the Good Will Hunting veteran out to dinner to discuss the possibility of working together on a new project, and Damon jumped at the chance to use the film, about the fight to stop gas company workers from drilling in a small town, as his directorial debut.
The Office star tells U.S. breakfast show Today, "He said he wanted to direct... 'Do you have anything that you might want to work on?' And I said, 'Yeah actually.'... And we were writing right away. He loved the idea."
Damon bowed out as the filmmaker due to scheduling conflicts and handed the project over to Gus Van Sant - but he still co-wrote and starred in the drama with Krasinski.
And the 33 year old jokes it was a struggle trying to concentrate at Damon's house - because he has four daughters, three with wife Luciana Barroso, and one from her previous marriage.
He adds, "He was actually shooting We Bought A Zoo out in California at the time and so I just drove to his house every weekend... he wins by default (because of) the four girls. So that's a very busy house... and we actually wrote with children climbing all over him. He was doing bath time and dinner and everything, and we still got it done."