Start a "trash mob" clean-up in your neighborhood.

Today I was in Baltimore, and it happened to be the day of a "trash mob" event--all you have to do is show up at the time and place listed, for just an hour, and help collect trash as a group. Surprisingly enjoyable, and undeniably rewarding. For an extra boost of fun, and as an added incentive, this group organized it as a "Harlem Shake" dance, inviting people to bring costumes and help make a clean-up themed video. So if you click through to the link, you'll see a quick glimpse of what this looked like! Even if you don't live in Baltimore and you can't participate in a "Zero Litter" clean-up event, I highly recommend you try this in your own neighborhood.