The 43-year-old actress - who has children Apple, 11, and Moses, 10, with ex-husband Chris Martin - said she has made a "bunch of changes" to her life since reaching the landmark age, reported Femalefirst.
"At 40, my life changed so much. I think every woman around that time gets this massive software upgrade. You're just different. You're upgraded.
"For me there were just a bunch of changes I had to make to really be true to myself and really live my happiness. And you have to be brave and make the choice to do that, to truly accept yourself and love yourself and really forgive yourself for your mis-steps.