I recently discovered a blog called The Non-Consumer Advocate whose motto is "use it up, wear it out, make it do, or do without." I've been focusing on using up food recently. I've got all sorts of weird ingredients sitting around the fridge and the cupboard that I either bought for a specific recipe or got because I thought it looked interesting. I happen to think that spices last much longer than their expiration dates, but I did notice that I have some non-spice items that are getting sort of long in the tooth. So I'm concocting recipes where I can use these things up so that I don't have to wait until they go bad and then throw them out.
Sometimes when I buy a special ingredient for a recipe, I think of it as "really special" and don't want to waste it by using it. I realize this is kind of irrational -- it's much more wasteful to buy it and not use it! I don't want to get bogged down by foodstuffs that I'm not using regularly, so I'm going to try to put more thought into my ingredients purchases. I tend to make mostly the same things, and I tend to like pretty similar food -- either really simple stuff like eggs and potatoes, or stuff that doesn't require fancy ingredients like Italian food, or delicious Indian food which is kind of complicated, but I do have all those spices on hand -- so I think I'll try to curtail my purchases of ingredients outside the regular rotation, so that I won't have any more five year old bottles of mustard oil that I'll have to try to make use of in the future.