Oprah Winfrey struggled to cry on cue for Steven Spielberg.

The media mogul and talk show host says acting allows her to leave herself behind and take on a new role as a character, but she doesn't always find it easy.

She told UK TV's 'Loose Women': ''I think my greatest acting lesson was the time I couldn't cry ... Steven Spielberg asked me to cry and I couldn't cry.

''And my [co-star in 'The Colour Purple', Adolph Caesar] said, 'You have to learn to give yourself over to the character and let the character take control and if she wants to cry she will cry and if she doesn't want to cry then not even Steven Spielberg can make her.''

Oprah told how the guidance from Adolph - who passed away in 1986 - made her learn to really embody the characters that she was portraying and helped her with her latest role as Gloria Gaines in 'The Butler'.

She added: ''I learnt to give myself over to that space with Gloria.''

The 59-year-old star gave up fronting 'The Oprah Winfrey Show' two years ago after 20 years, but insists despite what people say, she's not a control freak.

She explained: ''I think people think that because I run my own show and have my own business and run a network, that I have the need to be in control. Well, I really don't. What I have the need for is to surround myself with people who know what they're doing and are willing to do it.''