When I was young I would easily throw away paperwork thinking that nothing would happen to it, that the paperwork was just going to the dump. After working at a collection agency for 8 years I heard many stories of people that were a victim of identity theft. I then learned to shred anything that had my personal information like social security numbers, bank account numbers and so on.
I now have a shredder that can shred up to 10 sheets of paper at once and can also shred credit cards and staples.