The Labor Day actress, who will be attending the film's premiere at the London Film Festival later this month, spoke in a refreshing interview about her body confidence.
"Look. I'm 37 years old," Kate told Time Out. "We have one life. I don't want to spend my time thinking about the size of my a**e.
CLICK ON PHOTO FOR GALLERY OF KATE
"I want to be as healthy as I can be, and I want to have as much fun as I can have. I want to be around for my children. That's it. Those are the priorities. Not getting a flat stomach.
"Don't get me wrong. I like staying fit and healthy. It's all part of a healthy attitude to life."
The expectant mother is due to give birth to her third child, and her first with husband Ned Rocknroll, in just a few weeks. Kate already has 12-year-old daughter Mia and nine-year-old son Joe from her previous marriages.
The Hollywood star, who said she has been "lucky" and not had any major problems in her pregnancy, revealed that she wasn't going to rush into shedding her post-baby weight.
"How does anyone have the time?" said Kate. "Also, let's be real here. Everyone is different. Springing back into shape after a baby — that's not really something that's ever happened particularly swiftly for me. That's just me."
The Oscar-winning actress, who found fame at the tender age of 22 when Titanic came out, also spoke about how she's stayed so grounded through the years.
"I was raised to be a decent, polite person and I just could see that with some people they changed, that terrible sense of entitlement can kick in," said Kate. "I never felt that I was in any way entitled to be a little a******e. I just don't believe that that's how you should be in life, famous or not."