Michelle Obama Sings a Stevie Wonder Hit To Ryan Seacrest

First Lady Michelle Obama appeared on Ryan Seacrest's nationally syndicated radio show on Thursday to promote the Affordable Care Act and discuss her healthy lifestyle - even fitting a dig in about the entertainment personality's height.

"My mom used to always say that if I eat certain things, I would grow to be a certain height. It didn't pan out, would you say that that's accurate when moms say that to their kids?" Seacrest jokingly asked during a conversation about healthy eating.

"But just think about how short you'd be," Obama quipped.

Seacrest, who is the host of "American Idol," also asked the First Lady what song she would sing if she were to audition for the talent competition.

"I think by now people know that I love Stevie Wonder. He is a musical genius. He is one of my favorite artists of all time. And I would probably sing, 'You Are The Sunshine of My Life,'" she told Seacrest, even singing a line from the song to him. "And then people would press a button and kick me out or whatever you do."

The lighthearted interview did touch on one serious topic - the White House's hope that more young Americans sign up for health insurance under the Affordable Care Act. The White House is reporting that more than 3 million Americans have already signed up for health insurance through the state and federal exchanges since Oct. 1, but that number still lags behind pace to hit the target of 7 million enrollments by March 31.

"I always joke about this, the young people are the ones out at the club at 3 o'clock in the morning and who's more likely to slip on some ice," Obama said. "And young people are doing these pickup games, all of sudden they're just going to play volleyball. Beach volleyball. Well, you twist your ankle, you cut yourself because you're just learning how to cook. I mean, you know, life throws you some curve balls, and young people in particular need to have insurance."

Speaking of age, the First Lady celebrated her 50 th birthday earlier this month in Hawaii and with a blow-out dance party at the White House.

"I'm 50, I think everybody in the country knows that I am the 50. Just in case you missed it," Obama said. "But you know, quite frankly, I think everything gets better with age. I said this previously, but you know yourself more, you're not concerned about what other people think. If you've taken care of your health, many times this can be, you can be in the best shape you've ever been in."

As for her Valentine's Day plans with the president, Michelle Obama said she's planning on a "low-key day."

"It feels like we just finished celebrating my birthday, so I think we'll low-key it," she said.