Nicole Kidman's children are her "greatest joys" and being a mother has given her fulfillment in her life.The 'Paperboy' actress is delighted she has experienced motherhood in so many different ways - adopting Isabella, 20, and Connor, 18, with ex-husband Tom Cruise, falling pregnant naturally with Sunday Rose, four, and using a surrogate for daughter Faith Margaret, two - and admits her personal fulfillment comes from family life.Nicole - who has her younger daughters with current spouse Keith Urban - told Grazia magazine: "I think for every woman it is different, what fulfills you in life. I never thought I'd get to experience motherhood in terms of giving birth to a child."I've experienced many different ways of how to become a mother because I have adopted children, I have birth children, I have a child through a surrogate. The greatest joys for me have come through my children."And Nicole also feels "fortunate" to be married to Keith and says she never takes any of their time together for granted.She added: "I've always wanted a partner in life, it's just who I am. I am not a loner. I've been very fortunate to find him. I don't take any day for granted in relation to a relationship - I think that's probably the greatest advice you can be given."