What`s the best way to destroy CDs?

What`s the best way to destroy CDs? This question has been asked before (sort of), but I`m looking for a good, easy way to destroy CDs - on a once-in-a-while basis, not on an industrial scale, like the previous question. Basically, I want to get rid of old backup CDs but I want to be sure that the data on them cannot be accessed. At the moment, I put them in a bag and hit them with a hammer a few times, to break chunks off them. Is there an easier way?