"I thought I knew what love was, but holy cow, I did not. I could never have imagined the kind of love I have for my children. I am who I am because of my daughters. I'm an overachiever parent, and not because I think I'm going to repeat the patterns of my parents," Barrymore told Good Housekeeping.
Barrymore's own upbringing was less than traditional, a childhood she doesn't fear her children will share.
The 41-year-old actress says she focuses on earning her happiness.
"Happiness is not this yellow, blithe, floating thing. It's something that takes a tremendous amount of work. There's a warrior aspect to being happy. You've got to fight for it. And only when you've got that kind of earned happiness is it really good.