"You have to get over it. That's my term for the millennium," Sarandon told CBS This Morning Co-Anchor Mark McEwen.
"Let it go so life can find you again, and so you can get on. It's something that started with Dead Man Walking as a theme I was interested in."
In Stepmom, Sarandon plays Jackie, a divorced mother of two who finds she must share her children with her husband's new young wife, Isabel, played by Julia Roberts. The two characters get off to a rocky start as Sarandon's strong character feels she is being replaced as a mother. To add to her struggle, she discovers she has cancer.
"I asked that she [Jackie] do a couple of unsportsmanlike things because I didn't want her to be too good," Sarandon says. "I don't think that she thinks she'll go down with this one. I think that she's so strong and she's such a super mom that that's really a character that's way off there."
But what stops her dead in her tracks, Sarandon says, is the realization that her battle with Isabel is affecting her children.
"Mommy, if you want me to hate her, I will," Jackie's seven-year-old son Ben (portrayed by Liam Aiken), tells his mother, referring to his new step-mother.
From that moment, Jackie finds herself learning to grow with her new family situation, as opposed to focusing on how her illness is tearing her apart.
"We're trying to make points in this film, but we didn't want to be distracted by going in depth into my [character's] disease," Sarandon explains. "I wanted instead for this journey to be a spiritual one in which, though her physical self is diminishing, her glow is getting stronger."
Sarandon says that Roberts' professionalism made her work easier. While there are always rumors about cat fights between leading ladies, Sarandon says that didn't occur on the set of Stepmom.
"I think the operative thing that made the movie go well is that she's so great at what she does," Sarandon says. "It wasn't our friendship. In fact, if you're friends with somebody and they're not up to speed, it's going to hurt your friendship. Your friendship's not going to get you by if you're not delivering."
While Sarandon has blazed a trail for other actresses by portraying strong, intelligent women, and is a heroine to many of her female fans, she says she finds her own inspiration in other women.
"You know, I'm inspired by my life and the people around me because I have a very hands-on life," Sarandon says.
She says that she makes certain she is not isolated as many celebrities are, because she is better able to meet everyday women whosreal life stories amaze and educate her.
"Those are the women that just move me - mothers everywhere just kill me," Sarandon says.
Sarandon has starred on Broadway and in several critically-acclaimed movies, including Bull Durham, Thelma and Louise, Lorenzo's Oil, and the cult classic film, The Rocky Horror Picture Show.