The actress – who has two children Apple, eight and six-year-old Moses with husband Chris Martin, 35 – admitted she was not looking forward to reaching the milestone age on September 27 but now that her birthday is over she feels “happy and content”.
She told Us Weekly: "I was really worried about it, leading up to the day, but now I feel really happy and content with my life. I'm excited to move into the next phase. It's much more exciting than I thought it would be.
"I think I try to promote self-growth and reflection for myself every day.”
Although she is an Academy Award winning actress with a rock star husband, Gwyneth insisted they are no different to any other family.
She said: "We have a scrimmage soccer game in our yard every day after school. It's so fun. Though Moses prefers soccer, Apple has been really loving gymnastics.
"I feel that mental happiness and physical happiness are so closely related, and especially for kids, because they have so much energy."