Happy 40th birthday to @kellyclarkson! The original American Idol is celebrating her big 4-0 like any 40-year-old would do: "Low key." "I've had a crazy two years," the Grammy award-winning singer told E! earlier in the month about her plans for April 24. "So I just wanted a chill birthday." On Friday, her daytime talk show @kellyclarksonshow marked her milestone birthday by surprising the TV host with the cast of her favorite show, "The Rookie." Actor Michael Ealy also honored Clarkson with a serenade of "Happy Birthday" and a giant cake. We're marking the occasion by looking back at some of Clarkson's most inspiring quotes on life, family, and more. Follow the link in bio for more. 📷: AP, Getty Images, USA TODAY Network