Natalie Portman has revealed that she was unable to switch off from her character in Black Swan (2010) because she constantly had training to do.

The actress admitted that her role of ballerina Nina was "challenging" because of her heavy conditioning schedule.

Portman, who won the Golden Globe for 'Best Actress', told Bang Showbiz: "I like to shut off the character as soon as I'd finished, whether that's finishing a take or going home for the day. It was really difficult because I had so much training outside of work to do. When work was done then I had to go to the gym, and then I had to get up at 5am and work out before. There wasn't really any time to just relax and be myself."

The 29-year-old also said that it was difficult acting while physically pushing herself in the part.

She laughed: "Balancing the physical with the emotional because sometimes just to do a certain move you need so much concentration, my mouth would be hanging open and I'd have a concentration face, it'd be all furrowed."

"Half the time they were just trying to get me to not have my tongue sticking out. And then to add on to that I have to be acting!"

Source: Press Release