CHICAGO (CBS) — First lady Michelle Obama was greeted like a rock star by her biggest fans, hundreds of Chicago public school students.

She was in town Thursday to kick off a new fitness initiative. As CBS 2’s Dana Kozlov reports, the first lady even put on her workout clothes to help do it.

Mrs. Obama spoke more like first mom today, urging the hundreds of school kids listening to take care of their bodies and make smart choices.

“You and you alone have the power to choose the life you want for yourself,” she told students at McCormick Place.

Then, the first lady backed up her talk and worked up a sweat alongside the kids she’s trying so hard to motivate, with some of the world’s top athletes, like gold medal gymnast Gabby Douglas and 49ers quarterback Colin Kaepernick and tennis phenom Serena Williams.

Giving students more help to stay active was the real reason the first lady hit Chicago, announcing the “Let’s Move Active Schools” program. It’s a collaboration with businesses such as Nike to help funnel resources to schools for enhanced physical education programs.

Mayor Rahm Emanuel helped introduce the event on the same day he’s introducing a new initiative that will standardize physical education here.

In addition to a standardized curriculum, Chicago Public Schools will double the number of school-based gardens and work with the park district to find increased space for physical activity.

It’s possible “Let’s Move Active Schools” grants could help those efforts down the line.