Paltrow plays a hugely successful country singer battling personal and professional demons.
It was the first leading role in seven years for the Oscar-winner, who took time off to be with her two young children.
Paltrow told "Early Show" co-anchor Erica Hill Thursday it "was a lot of things" that lured her back. "I loved the story. I really loved the relationship between my character and Tim McGraw, (who played) her husband. It's like a portrait of a long-term marriage that was kind of disintegrating. I thought it was a really fascinating subject.
"And I loved the music -- you know -- the idea that I could learn how to play guitar and sing country music. I knew the music would be amazing and it would be like a really great focal point of the movie."
Paltrow says she "didn't know that I would fall in love with it the way that I did. I really loved doing it so much. I loved the whole process of learning and just being able to now sit with my kids and play guitar on the floor with them and make up funny songs. It's just opened up this whole other world. It's just amazing. I never thought that at my age I would learn a skill like that."
Her kids, Paltrow says, "think it's funny. They think I'm the guitar player of the house. … They're a little misguided!"
Paltrow is married to Coldplay front man Chris Martin.
Any chance of collaborating with him?
"Everyone's ruled that out!" Paltrow laughed.
She also addressed the difficulty of balancing her work and home life - and talked about a possible return to "Glee":
frontman of the British rock band Coldplay