Julia Roberts has revealed that filming August: Osage County was emotionally draining.
The actress has received an Oscar nomination for her performance of bitter eldest daughter Barbara Weston in the big-screen adaptation of Tracy Lett's Pulitzer Prize-winning play, which also stars Meryl Streep.
"It was just so hard. I knew it would be a great challenge, which was very appealing, but I didn't realise how continuously challenging it would be throughout filming," she said.
"I had seen the play, which... was three-and-a-half hours of being pummelled, it was amazing."
She added: "Most days, I think we were just exhausted. And it really is the benefit of the hard work that is always the next day's work. There was never any time to talk about or to examine the day's events."
Julia said the cast worked hard to prepare their lines in advance.
"Because the dialogue is so tricky, we all felt as a group that the priority was to have that down so that we could figure everything else out when we got there. We all wanted to... be off book," she said. "That way we would be ready to figure out the emotional landscape of what was going on and have the technicalities behind us."
The 46-year-old admitted that swapping her happy-go-lucky nature for her resentful and spiteful character wasn't easy.
"I am so nauseatingly optimistic in my real life and just pretty happy in general, that I had to really figure out the math of what makes Barbara behave this way and have these conflicts and this kind of access to bitterness," she said. "There was a lot more work and understanding to figure out who all these people were and how they could behave like this."
August: Osage County is released on January 24.