We moved to a smaller place 1.5 yrs ago, and I am NOT interested in a bigger place. We will just end up filling it with more stuff. I'm not interested in paying for, cleaning, or maintaining any more than what we have. I'm pretty ruthless. There are Christmas gifts that went straight to the regifting box when I got them home!
I like the idea of having only one more of things than what you need. If you are three people, have 4 bowls. That kind of thing.
I come from a family where my mother is always convincing herself how much she "needs" something. She has no ability to discern wants from needs. Sometimes I play a bit of a game with myself. If there is something I think I want or need, I see how long I can go without. I have been pleasantly surprised at how the universe sometimes presents you with those things you DO need. I got a bike from a coworker for free after mine was stolen (I wasn't riding anyways with a new baby) and finally got the stainless steel colander of my dreams at a yard sale - brandnew for $2, just minutes (literally) after putting it back on the shelf in the store. Of course, sometimes I figure out a solution with something I already have at home, or find out that I don't really need it.
If you don't use it in a year, if you can't find it or if you forgot you had it, ditch it.