Michelle Obama says her anti-childhood obesity campaign is "changing the conversation" in America.

The first lady says the nearly 4-year-old effort is creating a "cultural shift" in how we live and eat, and is beginning to have a positive impact on children's health.

One example she says she couldn't imagine when the "Let's Move" program launched in 2010: TV ads for egg-white breakfast sandwiches.

But Mrs. Obama says that while progress has been made there's a long way to go before the childhood obesity problem is solved.

She spoke Friday at an event highlighting the part of the program that encourages teachers and others to incorporate physical activity throughout the school day.

The first lady was joined by retired NBA player Shaquille O'Neal, sprinter Allyson Felix and gymnast Dominque Dawes.