I feel bad.
For a long time I've just replaced a flat tube with a new one and thrown away the old (although I always keep a couple old ones hanging from the rafters to make rubber washers and other assorted rubber doohickeys.) I think it was from bad experiences with patched tubes, which was caused by poor gluing - not enough area and not waiting long enough for it to dry. This summer I replaced a tube on my Bob trailer and reused it because I wasn't going to be able to buy a new one for several days, due to my remote location. I was careful and methodical and it worked great - held air as well as the new tube.
Now when I think about all the wasting I did by not recycling, I feel bad. I'm a recycling crusader, and yet I wasn't recycling my tubes!
I'll try to do better.