Childhood obesity isn't some simple, discrete issue. There's no one cause we can pinpoint. There's no one program we can fund to make it go away. Rather, it's an issue that touches on every aspect of how we live and how we work.

I think the most moving part of my trip [to Africa] so far was seeing 92-year-old Nelson Mandela, and just thinking about his life. This man has lived through a struggle that few nations have known.

We can make a commitment to promote vegetables and fruits and whole grains on every part of every menu. We can make portion sizes smaller and emphasize quality over quantity. And we can help create a culture - imagine this - where our kids ask for healthy options instead of resisting them.

Women and girls can do whatever they want. There is no limit to what we as women can accomplish.

All of us are driven by a simple belief that the world as it is just won't do - that we have an obligation to fight for the world as it should be.

I think any family would, any mother would their children.

In our house we don't take ourselves too seriously, and laughter is the best form of unity, I think, in a marriage.