In the movie, which co-stars Diane Keaton and Harrison Ford, McAdams plays a producer working for a low-rated morning news program.
"I tried to talk (director Roger Michell) out of (hiring me) a few times and, thankfully, he didn't listen to me. I was very nervous about playing this character and taking on this part and I didn't want to let him down. So, yes, I was very hesitant and we talked about it a little bit … and I'm grateful to him for that and it was a lot of fun," McAdams told reporters at a recent press conference in New York.
"What Roger did for me was get me out of my head and into my body," she added. "I grew up playing sports and that is the best way I work and it's a testament to him that he figured that out. He just said, 'Run around and wave your arms a lot and something will happen.' So, that's how I got through this movie."
"I have enjoyed watching her for years," Michell said of McAdams in a separate interview. "My teenage daughter used to drag me to films like 'Mean Girls,' so I have been aware of Rachel for quite a long time. In fact, before this project, I was wooing her for another project. She's notoriously difficult to woo. She's a very personable, very friendly person, but she's very, very cautious about her projects and one of her concerns about taking on this project, she confessed to me, is that she didn't feel that she is a comedic actress. She was worried that she wasn't funny and I reassured her and said we would figure it out because funny doesn't mean putting on funny faces and falling over funny. Being funny comes from something about you, something truthful in you that you push with a certain emphasis."
Michell said he knew the first day of rehearsal McAdams is "immensely physically funny."
"She's a gifted physical comedienne," he said. "From that moment on, really, every single day we shot -- and, of course, she's in every single scene in the film -- every single day she'd come to the set and bring a new flavor or energy or enthusiasm or idea … She's incandescent in the film and I really think this is her film and, hopefully, this will be her breakout film; whatever that expression means. "
Celebrity Families of 2014 [PHOTOS]