Cameron Diaz’s Serious Side

Cameron Diaz is known for her goofball roles, but in "My Sister's Keeper" the 36-year-old actress shows off her serious side.

In the drama, opening June 26, Cameron plays Sara Fitzgerald, a mother of two. Her older daughter, Katie (Sofia Vassilieva), suffers from a rare form of cancer. When younger daughter Anna (Abigail Breslin) discovers she was conceived for the sole purpose of keeping her sister alive, family bonds are put to the test.

In extras from this week's upcoming issue of Parade, Cameron talks to Jeanne Wolf about how she channeled her maternal instincts for the role, as well as her own parental relationships.

On getting in touch with mothers who've faced the real-life tragedy:

"I met with some wonderful women who were unfortunately going through the struggle with their children and their families. I felt like we all have those days where we want to be apathetic. And you just want to lie in bed for a second or just go, 'Leave me alone.' But the women I talked to don't have that luxury, not even for a second out of the day."

See exclusive photos from our sexy shoot with Cameron Diaz

On finding joy in sadness:

"In the film, my daughter is not always dying. Sometimes she's living. You have to celebrate that. The family has to find those moments, where we're like, 'She's alive and let's just take advantage of it.' The one thing I really love is that it's a love story on so many levels. It's all the things that we fall in love with in our lifetime -- falling in love for the first time, parents falling in love with their children, children falling in love with their parents. We all fall in love with our parents."

On losing the one she loved the most:

"My father passed away while I was in the middle of filming. I took time off to do what I had to do with my family. And then I had to go back to work. How if affected my performance I can't tell you, but certainly my father's death will be a part of me forever, and I'm sure it's going to be a part of all of the roles that I play now. It's been a year since he died, and it's been an incredibly transformative year. It's just something that's going to be with me forever."

See photos of Cameron and other Models Turned Actresses

On dealing with grief:

"There's tons of books about all the different emotions that you go through. And I definitely think that I've been through most of them. I've taken this past year off and I've been with my family mostly. My mother is the most amazing woman. She's the pillar of strength for our family. And so we're really lucky that we have a really strong family. No one crumbled underneath all of this. When it happened, people said I was hospitalized, which is of course the furthest thing from the truth. I was devastated, but certainly not hospitalized."

On the sense of humor she inherited from her dad:

"He gave me a really twisted sense of humor. I have a twisted vision of the world. But I'm a realist. I have very little delusion, I think. Maybe that makes me delusional. But, anyway, I love to have fun."

See photos of Ageless Superstars

On what's guiding her:

"Life is full of ups and downs. You can't know happiness without sadness and vice versa. The great thing about getting older is you become wiser. And you gain knowledge. And you grow. There's nothing wrong with that. That's a wonderful thing. I don't have to prove anything to anybody because I know who I am. I have my own sense of myself. The things that I do, I do for myself. I do them to challenge myself. And I do them to have my own experience. And, hopefully, I'm also giving something back to the world."

Click here to read the rest of Cameron's interview, including her feelings on men and getting older, or check out the latest issue of Parade in this Sunday's newspaper. And, for more on "My Sister's Keeper" and other new films, be sure to check out Yahoo! Movies' Summer Movie Guide.