Her name is Sandra Steingraber, and she's in jail right now protesting against a company that moved into her state, bought up land, and started putting polluting chemicals into it. The video is an interview Bill Moyers did of her a few days ago.
You don't need to do that to make a difference. Most of us can do plenty of things that can make the world a cleaner place. Why not pick one or two that you haven't done yet?