The Iron Man actress insists she doesn't have a problem with getting older and feels very comfortable with herself these days.
He said: "I was a mess in my 20s! I would never want to go back.
"I'm so thankful to bewhere I am."
The 43-year-old actress - who has kids Apple, 11, and Moses, nine, with ex-husband Chris Martin - is finding her current decade "incredible" and feels more "beautiful" now than she did when she was younger.
She told PeopleStyle: "I wish more women had told me that at 40 you sort of stop worrying about what other people think about you, and you come into yourself in the most phenomenal way.
"I think the 40s are such a gift, and I feel more beautiful now than I did 10 years ago or 20 years ago."
And Gwyneth thinks a lot of her beauty comes from feeling comfortable in her own skin. She said: "I think even though physically I don't look like I did when I was 25, I feel beautiful because I feel like myself."
However, the Mortdecai star isn't perfect as she has bad hair days "all the time" but insists she is fine with her "crazy" locks.
She said: "My hair is like three different textures. I usually just leave it, and I'm like, 'Whatever. I woke up like this. I don't know what to tell you.' "
