Michelle Williams says motherhood is at the ''centre of everything'' she does.

The 36-year-old mother has 11-year-old daughter Matilda Rose with her late husband Heath Ledger - who tragically died in 2008 aged 28 - and the star has revealed she struggles to separate herself from being a parent, and everything she does, including her work, is based on being a mother.

Speaking at a press conference at Cannes Film Festival for her new movie 'Wonderstruck', the blonde-haired beauty said: ''I think when you become a mother, it's sort of difficult to separate yourself from being a mother.

''Being a mother is not only who I am in my relationship with my daughter, but it's a part of the kind of work that I wanna make and the relationship with the person that I want to be for her. So there is really no area of my life that is untouched. It's at the center of everything that I do.''

Michelle plays the role of a single mother in the upcoming drama film and has revealed how learning how to respond to a child and connect with them helped her get into character for the production.

She explained: ''What I find most interesting about motherhood in this film, and everything that I make about being a mother, is being responsive to the child that you are connecting to.

''Personally and professionally, the great [trick to] working with children and knowing children is listening to children, and responding to who they are. Not your idea of a perfect child, not who you want them to be, but who they really are.''

Michelle has given her daughter the freedom to let her be who she is.

She explained: ''For Mother's Day, my daughter gave me a card that said, 'Mom, thanks for letting me be me,' and it was a picture with somebody in high heels on a skateboard.

''That's my ultimate [goal]; that's what I want them to do.''