This photo released by Entertainment One Films US shows, Penelope Cruz, left, as Gemma, and Emile Hirsch, as Diego, in a scene from the film, "Twice Born." (AP Photo/Copyright Entertainment One Films US)

LOS ANGELES, Calif. - Forgetting Penelope Cruz is almost 40-years-old is easy to do.

Even when she bears heavy makeup to add wrinkles for her role as Gemma in the wartime melodrama "Twice Born," it's nearly impossible for the actress to truly look weathered.

When pressed against 28-year-old co-star Emile Hirsch during love scenes, the bond seems natural and comfortable.

The Sergio Castellitto film opens in limited U.S. release on Friday after first premiering in Italy last year. It's based on the book of the same title, written by Castellitto's wife, Margaret Mazzantini.

"I could not put it down," said Cruz of the tale set amid the Yugoslav Wars. When Gemma and Diego (Hirsch) fall in love during the 1984 Winter Olympics in Bosnia, they both discover they desperately want children. But Gemma is unable to conceive.

"It's a 700-page book and I read it in a day and a half and was blown away by the character," said Cruz, who also produced the film. "Every role makes me feel like I'm a student," Cruz added via Skype from London. "It's a great feeling."

Cruz became involved with the film early-on, including casting. Emile Hirsch was Cruz's ideal choice for the role of Diego. "I think he is an incredible actor," she said. "I have seen most of the things that he has done. I especially loved his work in the Sean Penn-directed, 'Into the Wild.'"

She also came to love Hirsch's methods.

To "make sure things didn't get boring" between takes, said Cruz, Hirsch would playfully strike up an argument.

"Like he would come to my trailer and say that he'd just seen a documentary on a scientist that did blah, blah, blah . but it would stump me," said Cruz. "So I would fight him."

This was Cruz's second collaboration with director Castellitto — she teamed with him on the 2004 film "Don't Move" — and the actress was encouraged to take on the larger role of producer, since she's been dabbling behind-the-scenes more and more of late.

Earlier this year, she directed a commercial for her L'Agent lingerie line — a collaboration with her sister, Monica Cruz, and Agent Provocateur.

Next, the actress will direct another L'Agent spot and she'll produce and star in Fernando Trueba's feature "La Reina de Espana."

Cruz remains eager to continue expanding her artistic reach — just as long as her packed schedule doesn't take her away from loved ones for too long.

"Family is my No. 1 priority," said the busy mother of a baby and toddler with husband Javier Bardem.

"There are so many things that I think about now that I didn't think about before," she continued. "When I look at what I'm going to do next and when, where, how, I think about my family."

Being a mother, she added, "is the best thing that can happen to you in your life."

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Follow AP Film Writer Jessica Herndon on Twitter at: https://twitter.com/SomeKind

News from © The Associated Press, 2013