At just 16 years old, Greta Thunberg is already one of our planet’s greatest advocates. Her age might have something to do with it. With full knowledge that her generation will bear the heaviest burden of climate change, she’s unafraid to believe that progress is possible—and fight for real change. She’s an example of why Michelle and I started the Obama Foundation — because we believe in a future that’s shaped by the courage and hope of young people like Greta.