Curtis is shown sporting gray hair and wading in water up to her chest on the cover of the magazine's May/June issue, which will be available Monday.
The star of "True Lies," "A Fish Called Wanda" and other films becomes eligible for membership in AARP, the nonprofit organization for people 50 and over, when she celebrates her birthday Nov. 22.
"I want to be older," she tells the magazine. "I actually think there's an incredible amount of self-knowledge that comes with getting older. I feel way better now than I did when I was 20. I'm stronger, I'm smarter in every way, I'm so much less crazy than I was then."
"I was like, `How dare you - I'm not 161 pounds!' I was indignant. I got home and I went on a scale and I was 161 pounds. I was in denial about it," she says.
"So I started a really healthy way of eating, just avoiding things that I had been shoving in my mouth. Over the course of a year, I dropped about 20 pounds," Curtis says.
2"Now, I get up at (5 a.m.) every day, filled with energy. I play tennis three times a week, and I do yoga."
Curtis says growing older means paring down to an essential version of yourself.
"I've let my hair go gray. I wear only black and white. Every year I buy three or four black dresses that I just keep in rotation. I own one pair of blue jeans. I've given away all my jewelry, because I don't wear it," she says.
What about her life would she do over?
"I've been an inconsistent parent at times, and it's my greatest regret," she says. "When my daughter was small, I worked too much. I was replicating what my own mother (Janet Leigh) did."