If your household is anything like mine, you get a small ton of junk mail in your mailbox weekly. I took a tip from an old friend a while back and started taking steps toward revenge. Since then, any time I get a piece of mail that includes a postage-paid return envelope, I simply write a note back to the company letting them know that I'm not interested in whatever it is they're trying to sell me, stuff it in the return envelope, and make them pay to have their own tree-killing garbage sent right back to them. You don't have to pay a cent! Sometimes it takes more than one attempt (Discover clearly doesn't get it), but our junk mail load is minuscule compared to what we used to get. I also recently learned that my incredibly awesome father-in-law does this too, only he stuffs various other things into the envelope to add weight, making the companies spend even more money to get their crap back. Give it a shot! It works.
Oh, and P.S....some of my notes aren't always this nice. Like I said, Discover clearly doesn't get it.