Challenge: Check out your local chapter of Freecycle, and sign yourself up!
Why: In my opinion, free is good. I think this is a fantastic way to preserve the lifespan of any object. Be it by passing it on to others instead of throwing it away or getting something second hand instead of brand new.
"The Freecycle Network™ is made up of 4,981 groups with 8,736,603 members across the globe. It's a grassroots and entirely nonprofit movement of people who are giving (and getting) stuff for free in their own towns and thus keeping good stuff out of landfills."
How: Head over to Freecycle, find the chapter nearest you, and sign yourself up. You can post things that you want to give away or things that you hope to find, all for free.