Why ‘Me Before You’ is Sam Claflin’s ‘Most Physically Challenging’ Role

— -- Emilia Clarke and Sam Claflin have played tough roles in blockbuster hits -- Clarke as Daenerys Targaryen in “Game of Thrones” and Claflin as Finnick in “The Hunger Games” -- but the actors got to show their full range of emotions in the new film, “Me Before You.”

Based on an international bestseller by author Jojo Moyes, the film tells the story of the relationship between a Will, successful young man who becomes a quadriplegic after an accident, and Louisa, the woman who is hired to care for him.

Clarke and Claflin chatted with ABC News’ Amy Robach about the film.

Bound by his character’s extensive physical limitations, Claflin could only rely on his facial expressions and the use of one hand.

"This was probably the most physically challenging thing that I’ve ever done,” he said of the role.

He also went on a 500-calorie per day diet -- combined with training -- to lose 40 pounds for the role.

“What was important to me was that the character looked quite frail and quite weak, when you first meet him post-accident,” Claflin said.

The book behind the movie was first released in 2012. It has since returned to the top of the New York Times bestseller list.

Moyes, author of the book and film’s screenplay, said of its title, "Most of us have one person in our lives who actually changes the way we think or encourages us to look outside our box and for me, this is what this story is about."

Clarke said her favorite scene was the wedding sequence, calling it “joyful.”

She added that she wanted viewers to see the film as “a really beautiful love story. Don’t take the life that you have for granted. Go out there and live it as fully as possible.”

Claflin said the final scene between the two characters had a profound emotional impact on him.

“It sort of unlocked something for me and I spent the entire day sobbing even when we weren’t actually filming,” he said.

“Me Before You” premieres on Friday.