Her daughters were 6 and 9, and Michelle Obama was like any other working mom — struggling to juggle office hours, school pick-ups and mealtimes. By the end of the day, she was often too tired to make dinner, so she did what was easy: She ordered takeout or went to the drive-through.

She thought the girls were eating reasonably well — until her pediatrician in Chicago told her he didn’t like the weight fluctuations he was seeing.

« I was shocked because my kids looked perfectly fine to me, » Obama says. « But I had a wake-up call. » Like many parents, however, « I didn’t know what to do. »

Today, the self-described « mom in chief » is launching Let’s Move, a campaign to help other parents deal with a national health crisis she describes in epic terms.

The goal: to eliminate childhood obesity in a generation.

« It’s an ambitious goal, but we don’t have time to wait, » the first lady said in an interview with USA TODAY in her spacious office in the East Wing of the White House. « We’ve got to stop citing statistics and wringing our hands and feeling guilty, and get going on this issue. »