If you're like me, you own a few pairs of athletic shoes for all your exercise needs. I have a pair for running outside on pavement, a pair for running in the woods, and a pair for tennis. When I buy a new pair of sneakers, I always hold onto the old pair "just in case."
One great thing about running is that you don't need a lot of gear to participate in the sport. Basically you need a good pair of sneakers. When your sneakers wear out, don't just toss them away.
I know Earth Day was last week but that does not mean you need to stop being green. The thing with sneakers is that not only are they expensive, but in order to get the most out of them you should get a new pair every few months. That's a lot of sneakers in landfills.