John Krasinski's new film, The Hollars, which he directed and stars in, tells the story of a man who is facing fatherhood while dealing with his own dysfunctional family -- and it turns out that being a dad himself played a big role in Krasinski's approach toward making the movie.
"We started shooting the movie when my daughter was 4-and-half-months-old, and I've got to say that, had I shot this five months before, that it would have been a totally different movie," Krasinski told ET at the New York premiere of The Hollars.
The 36-year-old actor and his wife, Golden Globe winner Emily Blunt, welcomed their first daughter, Hazel, in February 2014. Blunt gave birth to the couple's second daughter, Violet, in June.
WATCH: Emily Blunt Opens Up About Expecting Baby No. 2: 'I Forget That I'm Even Pregnant'
"All the clichés of parenting are true and you feel all sort of new things," Krasinski shared. "It was really this new existential magnet that you feel draw to your family… and you understand your parents more, you understand your brothers' relationships more, you understand even your family's name. That you are from somewhere."
"It was just very, very much more weighty than I expected it to be, so I was working a whole lot out in this movie," he added.
Being the father of a toddler and a 2-month-old, Krasinski couldn't help but marvel at his eldest daughter's relationship with her baby sister.
"She's amazing," he shared. "She really loves the baby and I think there is this idea of, 'Oh my God, she is adorable.' I mean when a 2-and-a-half-year-old hugs a newborn baby it's one of the cutest things you will ever see."
PHOTOS: The Most Adorable Celebrity Dads
Despite their busy home life, both Krasinski and Blunt are taking on some major projects. While Krasinski is preparing for the release of his sophomore directorial effort, Blunt is gearing up to star in the upcoming remake of Mary Poppins.
While his wife has apparently been rehearsing "behind closed doors," Krasinski said she has never sung in front of him outside of a sound studio in London when she was recording her songs for Into The Woods.
"I came to visit and they were doing the pre-records on Into The Woods, and I remember [director] Rob Marshall turning to me and he said, 'It's so great,' and I said, 'Yeah, I’ve never seen her sing,'" he recounted. "Rob Marshall did the slowest double take of all time and then queued a 125-piece orchestra and she started singing and I just wept. I told you that I am a crier, it doesn't take much."
Marshall and Blunt are teaming up again for Mary Poppins Returns, which is set for release in December 2018. Krasinski's The Hollars hits theaters August 26.
Reporting by Rande Iaboni
WATCH: Emily Blunt and John Krasinski Announce Arrival of Second Daughter Violet