On The Early Show Thursday, Diaz discussed her role in the Nic Cassavetes film, "My Sister's Keeper," in which she plays a mother whose daughter is fighting cancer.
Early Show co-anchor Harry Smith remarked that this must mean Diaz is "over the hill" and "history" now. Diaz responded, "Oh gosh, I love moms. I think they're awesome. I thought moms were making a comeback."
"I think we should worship mothers," Diaz added. "I don't think there should be any point or time that a woman should be considered 'over the hill' just because she's had a child. I think some women are better off when they become one."
Cameron Diaz, who didn't read the book by Jodi Picoult, said playing the mother role was led by the screenplay vision of Cassavetes.
"Nick wanted to make sure that there were moments when you saw the family celebrating that this child was alive and being a normal family, that while she was sick and close to death, that she was actually alive, and that's something to really embrace."
Diaz also shared the difficulty of returning to the film's production after her 58-year-old father, Emilio Diaz, died. She said she would rather not have come back, but going back to the cast and crew was a good thing.
"It was a blessing that it was the group of people that I was working with," she said.
Smith said his impression of the film was that there wasn't a false note in it.
Diaz said she loved to hear that, and has heard the same sentiment from others. "It's right on key here. It's true to every emotion. You don't go through this questioning about what these people are going through it, whether or not what they're experiencing it," she said. "And it isn't just one person's story, it's everyone's story."
Smith asked Diaz's co-star Sofia Vassilieva, of CBS show "Medium," what she had to do to take on the role of the sister who has leukemia.
Vassillieva said she did a lot of research and spoke with children at City of Hope, a cancer center, and tried to understand what they are going through.
"I think when you spend time around somebody, you pick up on the energy and just the way they present themselves, and you kind of get to the root of it," she said.
"My Sister's Keeper" will be in theaters nationwide Friday.