Kate Winslet often vomits before shooting tough scenes.

The 38-year-old star gets struck down by nerves that leave her feeling nauseous before hard parts in front of the cameras because she still has insecurities as an actress.

The Oscar-winning starlet said: ''I think you get really good at mind-f***ing yourself, to be honest. Acting is bloody scary. I still have moments when I think, 'I can't do this - everybody thinks I'm absolutely sh*t.' There are scenes I absolutely dread - there was a scene in 'Labor Day'; the whole courtroom sequence in 'The Reader'. I often throw up, which I'm a bit embarrassed about. It's the adrenaline.''

The blonde beauty - who has daughter Mia, 13, with ex-husband Jim Threapleton, son Joe, 10, with ex-husband Sam Mendes, and four-week-old son Bear with husband Ned Rocknroll - was cast as depressed, single mother Adele in upcoming film 'Labor Day', but believes she wouldn't have been able to do the role if she hadn't have had children of her own before.

She explained: ''It's a part I could not have played had I not been a parent. Ultimately, I was drawn to it because it's a film about the desire for a family - and family has played such a role in my life. It's my core, really.''