The actress, who has two children with Coldplay frontman Chris Martin, said that her personal fitness trainer made her do "crazy things" in order to transform her body for the movie.
Paltrow told Us Weekly: "My trainer, Tracy Anderson, basically, like, pummeled me into submission and made me do all kinds of crazy things. She really changed my body for this movie."
Talking about her workout routine since the movie, Paltrow said: "If I'm home with my kids, I still like to do it every day, but I don't go as crazy. I will do cardio one day and legs another day."