Kate Winslet is a busy actress this season, with not one but two serious dramas in theaters this month. In addition to reuniting with 'Titanic' co-star Leonardo DiCaprio in 'Revolutionary Road,' Kate gets emotionally -- and physically -- naked in the post-war drama, 'The Reader.'

"It really took me to the brink in many ways," Kate tells ET. "To bring [my character of] Hanna Schmitz to life was an absolutely enormous challenge and a huge responsibility as well, because it's a much-loved piece of German literature. Many people have differing opinions of Hanna Schmitz; they love her, they loath her."

A haunting story about horrific war crimes, truth and reconciliation, 'The Reader' stars Kate as Hanna, a woman in post-WWII Germany who plunges into a passionate and secretive affair with a younger man named Michael Berg (David Kross) and then suddenly disappears. Several years later, Michael, now a law student, sits in on the Nazi war crime trials, only to find Hanna forced to defend herself in the courtroom.

"It is a love story; it's not a Holocaust movie," says Kate. "It's about these two people falling in love and needing each other in ways that really surprise them both."

For the nude scenes in the movie, Kate says she refused to work out because, "It was important to me to look real. I really don't believe in this notion that actors and actresses should look untouchably perfect."

As for the fact that she's 15 years older than her 18-year-old co-star, she says that their love scenes were nothing but professional. "It was the same as shooting any other scene of that nature," she explains. "A scene with that level of intimacy involving nudity, you know, it's always nerve-wracking, and you really have to rehearse those scenes so that everybody knows exactly what's going on. … He didn't need that much looking after."

Directed by Stephen Daldry ('The Hours'), the film also stars Ralph Fiennes as the older Michael and Lena Olin as his therapist.

Watch ET for more with Kate and the cast of 'The Reader.'