Editor's note: Michelle Obama is first lady of the United States.
(CNN) -- Back when we first launched Let's Move! -- a nationwide initiative to end our childhood obesity epidemic -- in the back of my mind, I wondered whether it was really possible to make a difference.
I knew how serious this problem is. Nearly one in three of our children are overweight or obese, at risk for illnesses such as diabetes, heart disease and cancer that cost our economy billions of dollars each year to treat.
I also knew the conventional wisdom on this issue. There's the assumption that kids don't like healthy food, so why try to feed it to them? There's the belief that healthy food doesn't sell as well, so companies will never change the products they offer. And there's the sense that this problem is so big and entrenched that no matter what we do, we'll never be able to solve it.
But over the past two years, we have seen a new conversation in this country about how we live and eat and how that affects the health and well-being of our kids. Since we launched Let's Move!, people from every corner of this country who care about our children's futures have stepped up and proved the conventional wisdom wrong.
Food manufacturers have pledged to cut 1.5 trillion calories from the products they sell. Local grocers and national chains such as Walgreens and SuperValu are building new supermarkets and expanding existing stores to sell fresh food in 1,500 underserved communities. Restaurants are transforming their kids' menus, packing them with healthier options.
Mayors are planting gardens and refurbishing parks. Congregations are sponsoring summer nutrition programs for kids and exercise ministries for families. Congress passed historic legislation to provide healthier school meals, getting more fruits and vegetables and other nutritious food to the tens of millions of children who eat school breakfasts and lunches each day. We're also working to install salad bars in 6,000 schools, and more than 3,400 professional chefs have signed up to help schools improve their menus.
Celebrities from Beyonce to LeBron James to Drew Brees are serving as role models, inspiring our kids to dance, dribble and pass their way to a healthier life. And more than one million children have earned the Presidential Active Lifestyle Award by exercising an hour a day, five days a week, for six weeks.
Most important of all, parents all across this country are making important changes for their families.
They're pushing their kids to be more active. They're reading those food labels and rethinking the meals and snacks they serve. And they're coming together to advocate for healthier food in their kids' schools and more opportunities for their kids to get active in their communities.
In the end, that's really what Let's Move! is all about. Government certainly doesn't have all the answers here; there's no one-size-fits-all program or policy that will solve this problem. Every community and every family is different, and each of us needs to make changes that fit with our budgets, our needs and our tastes.
But in the end, we all have a stake in solving this problem because we all love our children and want them to have every opportunity to pursue their dreams. And we all love our country and know that we as a nation cannot fulfill our promise unless our children can fulfill their promise.
So we all need to step up and do our part. And while it won't be easy, I am confident that if we keep coming together and working together, we'll be able to give our kids everything they need for the bright, healthy futures they so richly deserve.
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The opinions expressed in this commentary are solely those of Michelle Obama.