Michelle Obama marked her 50th birthday with a picture of her brand-new AARP card Credit: Courtesy Michelle Obama

Fifty shades of great! First Lady Michelle Obama celebrated a milestone birthday -- the big 5-0 -- on Friday, Jan. 17, and promptly took to Twitter to show off her brand-new ID card from the American Association of Retired Persons.

"Excited to join Barack in the 50+ club today...check out my @AARP card!" President Obama's wife captioned a photo of herself holding the little piece of plastic. (The Commander-in-Chief is 52; he'll turn 53 in August.)

Last year on her birthday, the First Lady unveiled her official @FLOTUS Twitter account and debuted a much-talked-about haircut -- with bangs! She later joked that the new 'do was her "midlife crisis."

"I couldn't get a sports car, they won't let me bungee jump -- so instead, I cut my bangs!" she quipped in a Skype interview with Rachael Ray.

Speaking about aging in an interview with Prevention back in 2012, the mother of two confessed, "Women are definitely under a lot of pressure, but I think it's important to remember that to look good, you have to feel good. I look at my mom at 74 and see how beautiful she looks and how wonderful she is with our daughters and with me and my husband -- and I want that for myself when I'm her age."