Gwyneth Paltrow's sex life improved because of Tracy Anderson.

The 40-year-old actress sought help from the celebrity fitness trainer after giving birth to son Moses in 2006, and credits her regime for putting the spark back in her and husband Chris Martin's bedroom.

Speaking about the fitness method, she told Redbook magazine: ''It did such wonders for my life, my confidence, my sex life, everything.''

Tracy, who has also worked with Madonna, added: ''When you feel your best, you're more confident in bed, It's not lights-out, under-the-covers sex. It's more like, 'Take a look at this!'''

The 'Iron Man 3' actress - who also has an eight-year-old daughter Apple with the Coldplay frontman - celebrated turning 40 in September and though she wasn't looking forward to reaching the milestone age, she feels ''really happy'' how she has passed her big birthday.

She said: ''The morning of my 40th birthday, my children and husband woke me up with hugs and gifts, and I proceeded to have the best week of my life. I feel really happy being 40, now that I'm on the other side of it.

''There was definitely some uncomfortable anticipation. But I'm amazed at what I've been able to accomplish, that I've maintained my important relationships and have such incredible women friends, that I have two funny, beautiful children who can give me a real life. In a way, I feel like no one should make big life decisions until 40. It's when it all starts to settle and become clear.''