John Krasinski, Blake Lively and Ryan Reynolds Getty Images (2)

Take it from actor-director John Krasinski: peer pressure works.

During a stop on The Tonight Show With Jimmy Fallon on Friday, May 10, Krasinski, 44, said he used “emotional blackmail” to add Blake Lively to the ranks of his star-studded cast of IF, which already included her husband, Ryan Reynolds.

“I was like, ‘Everybody’s doing it,’” Krasinski said of his pitch.

In addition to Reynolds, with whom the Gossip Girl alum shares four children, Lively, 36, joined the likes of Krasinski’s former Office costar Steve Carrell, Bradley Cooper and George Clooney in the movie about the world of imaginary friends. She plays Octopuss, a cat that dresses up like an octopus to will herself past her fear of water.

Krasinski says he came up with the idea almost a decade ago while watching his kids play and felt a newfound urgency to complete it during the coronavirus pandemic.

I used to just stand in the doorway and watch my kids disappear into this magical world that we as parents aren’t allowed in,” he shared. “It actually wasn’t until the pandemic when genuinely I saw their lights starting to go out … I went, ‘That’s it, I’m writing this movie right now to prove to you that magical world is always there. You can always go back.’

John Krasinski, Blake Lively and Ryan Reynolds Ignat/Bauer-Griffin/GC Images

The idea resonated with Hollywood A-listers, as Krasinski said he received “the most ‘yeses’ of my career” for the movie. Clooney’s decision to take a role in the movie is particularly resonant for Krasinski, as he was the first person who saw the one-time sitcom star moving into the director’s chair.

“He was the first person who ever thought I would direct. He would take me to dinner while we were shooting Leatherheads, and he would show me a drawing. ‘This is what I’m going to shoot tomorrow. This is where I’m going to place the cameras,’” Krasinski told Fallon. “I said, ‘That’s amazing. Why are you telling me this?’ He said, ‘Well, you’re not just going to be an actor, are you?’”

Krasinski said that Clooney, 63, saw the desire to direct in him before he did, joking that he only “takes 10 percent” for his mentorship. The Clooney team-up was far from the only emotional reunion brought on by the film. A video shared by Paramount Pictures captured Carrell and Krasinski reuniting for the first time in years while making the movie. Krasinski told Total Film Magazine that Carrell’s speech to him soon after brought on the waterworks.

“As much fun as it was to work with him, the most powerful part about it was he came in with the most heartfelt speech about how proud he is of me to be making movies. He said in reading the script, ‘I’m just so honored to be a part of it. I’ll do whatever it takes,’” the director shared last month. “So when I thought that I would be laughing all day, I was crying all day.”