Gwyneth Paltrow,actress says she's in the best shape of her life.

Gwyneth Paltrow says she saw a photo of herself on vacation in Barbados and thought: 'All my hard work paid off!'

Gwyneth Paltrow is 38 and says she's in the best shape of her life.

"I never thought that I'd be considered to have a good body.  I was bony up top and kind of dumpy on the bottom," Paltrow says in the May issue of Self. 

It wasn't until she met celebrity trainer Tracy Anderson when Paltrow began her body transformation.  But despite the opportunity to work with a certified trainer, the actress reveals the secret to achieving her red-carpet worthy figure is simply done the old fashioned way: diet and exercise.

"I do 45 minutes of cardio five days a week, because I like to eat," she says. "If I'm prepping for something or I've been eating a lot of pie, I do two hours a day, six days a week for two weeks."

"I've found what works for me," she adds. "I know if I put in an hour and a half, five days a week, I'm good.  If I'm on vacation and, like, ‘F--- it, I'm not working out,' I know what to do when I get back.  A lot of women think, 'Oh, my God, I could never get there,' but I don't think that's true.  It's simply relative to how much you put into it."

Paltrow lists two things to help cope with her performance jitters: 'A Guinness and a beta-blocker.' (Mark Abrahams/Self)

And according to Paltrow, the amount of time she puts into exercise depends on the amount of food she's planning to consume.

"I like feeling strong and health, but mostly I think about the fried zucchini I'll eat later!" she admits.

While she snacks on raw almonds with raisins or a juice made of kale, lemon juice, water, Vitamix and agave, Paltrow admits her weaknesses lie barbeque potato chips.

"I say I always eat right, but last night, I had fried clams, pasta with duck sausage and two glasses of red wine," she told the mag. "When I want to lose, I eat less pasta, bread and potatoes.  Before last year's ‘Iron Man 2' premiere, I did green juices and salads for three days."

So how does the working mom - who's got her hands busy with a film career, new cookbook, lifestyle website, recurring stint on "Glee," among other projects – do it?

"I go with my instincts," she said. "We're capable of pushing ourselves and doing whatever we want to do.  You live one time, so be your best self."