Cameron Diaz is wise beyond her years.

"The Other Woman" actress is the cover girl for Women's Health magazine's April issue, and in her inspiring interview with the glossy that was released on Thursday, she gives her best life lessons on fertility, friendship and living a happy and healthy lifestyle.

WATCH: Cameron Diaz Says Sex Is Her Secret to Staying Young

"The most important things in my life are my relationships and my well-being -- where I'm going as a human being in my development mentally, emotionally and physically," Diaz explains.

We're so excited to announce our April cover star, the ever-glowing @camerondiaz!

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The 43-year-old star -- who has managed to balance a fun life with a highly successful career -- offers up advice for all women, even breaking down what females should and shouldn't do based on age.

"Bone mass is really important in your twenties -- after that, we don't build much bone anymore," The Longevity Book author says. "So your twenties are your best chance to build bone through nutrition, physical activity and strength training."

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Though she doesn't have any children of her own (yet!), Diaz -- who is married to Good Charlotte rocker Benji Madden -- also suggests that women should start getting regular child birth tests once they ring in birthday No. 30.

"After 35, most women's eggs start to dwindle," she points out. "There's no way of knowing until you test yourself. That might be something you want to do in your early thirties if your fertility is important to you."

As for what women should do in their 40s? Diaz reveals it's all about communicating and de-stressing!

"Make connections, make friends, join communities, and really honor yourself," she advises. "You're getting ready to make that transition to menopause, so pay attention to where you're at emotionally, physically and mentally. The women who stress have it longer and harder, but the ones who accept it have it shorter and less severe."

WATCH: Gwyneth Paltrow, Drew Barrymore and Cameron Diaz Have a Girls' Night Out

Having a good time with her close gal pals is exactly what Diaz has been doing as of late. Last December, the actress was spotted having a girls' night out with Gwyneth Paltrow and Drew Barrymore at Dirty French in New York City.