Sienna Miller reveals having a child has made her less ambitious

She is more known for her boho style, but even celebrities like to have an off day.

And mother-of-one Sienna Miller showed she can carry off the cowgirl casual style with aplomb as she went for a walk in the blazing sunshine in her new home New York City.

The 31-year-old, who admits she is less ambitious since becoming a mother, pulled on some boyfriend jeans and a loose green top as she headed out into the sunshine.

Casual yet chic: Sienna Miller pulled on a pair of boyfriend jeans and a checked shirt for her stroll in New York City

Her usual tousled hair was pulled back into a messy ponytail and she topped her look off with a retro pair of red rimmed shades.

The 31-year-old British actress - who gave birth to her first child Marlowe with her fiance Tom Sturridge last July - is happy to let her career take a back seat at the moment as she wants to watch their daughter grow up.

The Foxcatcher star told French newspaper Le Figaro's supplement Madame Figaro: 'My daughter monopolises my time. I spend my days making pureed food for her.

Less ambitious: Sienna said she is happy for her career to take a backseat to give her time to be a mother to daughter Marlowe

Making the most of the sunshine: Sienna does casual superbly as she strolls around NYC

'My life is this: my baby and my dog. My fiance is in a play at the moment, he's busy working a lot.'

Sienna originally planned to take a break immediately after having her daughter, but changed her mind when she was offered a role in Bennett Miller's forthcoming film Foxcatcher, which was shot in Pittsburgh, and while she enjoyed the experience, she now plans to resume her maternity leave.

Family time: Sienna was joined by her American banker father Ed Miller

Where's Marlowe? It looked like Sienna left her daughter at home for the shopping trip

She said: 'It was amazing to come back to film and work with director Bennett Miller on Foxcatcher, despite becoming a mother having made me not miss working in the industry. For the time being at least, I prefer watching my daughter grow up.'

The blonde star also revealed that her life is a lot more settled in recent years and it has made her feel much calmer.

She said: 'My twenties were a bit crazy. I spent those years working and being repeatedly persecuted by the media. Nowadays, I can be the woman I truly am, more calm, and freer too. I turned 30 and I suddenly had much less energy!'

She can do glam too: Sienna earlier this week at the Annual Tribeca Film Festival in a quirky black dress