She opened up about her marriage to musician Benji Madden, and reveals the best and worst things about tying the knot. Diaz, 43, agreed that marriage make a person happier, which can help improve the quality of life.
"Happiness actually has shown that when we're happy we actually live longer," Cameron said. "When we accept that we're aging we live longer. And being that our relationships are very, very important any kind of relationship it doesn't just have to be a marriage."
The "Bad Teacher" actress said it helps to have a reason to live. "Even if you're just engaged in something you really think is important. When you can grow with someone it's very important," she said.
When it comes to the best and worst parts of marriage, Diaz joked that it's all the same thing.
"Someone asked me, 'What's your favorite thing about being married?' And I was like, 'Well, I just learned so much about myself. I didn't know these things.' And I was like, 'I would have never known them if I didn't meet my husband, who helped me,'" Cameron told Ellen.
The actress then gave the same answer when asked what she views as the "worst thing about marriage."
"I learned all these things about myself that I wish I never learned about myself and I wouldn't have known them if I didn't get married," Cameron said. "So it's like this double-edged sword. But I'm just so grateful for it because I couldn't do it without my husband and I couldn't do it with anybody else except for him."
Cameron married Benji, 37, at her Beverly Hills estate in January 2015 after eight months of dating.