I have a rule here: When I didn't use stuff for a long time, I decide I also won't need it in the future - and it's being tossed away. Well, first of all this is for magazines and leaflets. When it comes to more expensive/valuable things, I usually make exceptions. :D But I just need space for my growing Pokemon plush collection, and I restructure my room a bit.
Cleaning up can be fun and nostalgia at the same time. It reminds me of what I was and what I did in the past. Good old memories come up. :D Bad memories as well. ^^ I can somehow close up with them by tossing away the things with the burden that lies within. It helps with letting go.
Man, I'm getting philosophic again. ;) Stop it! :D