This happens to everyone, I suggest putting it all in a box for a month or so. Place the box in a place out of the way, and then when the time is up, you will know whether or not you really needed it.
This is a tough one because I like to keep most things! I think if you haven’t used it in the past 5 years or if it isn’t an object that brings back fond memories or makes you feel happy about having it, I’d give it away. I’d donate mine to charity or give it to someone I know who will appreciate it. I sometimes try to sell mine. If I don’t really like it at all, I might take it apart and make something new (jewelry, arts and crafts, etc.) out of the parts if I think I’d like that better.