As someone who has moved 4 times before the age of ten, I've been conditioned to do a "full cleanup" once a year: Take one (or several) big trash bags and work your way through your room(s) bit by bit. Start with the shelf/closet/whatever to the left of the door and ask for every item "Did I use this in the last year? How likely is it that I will use it in the next?". If the replies are "no" and "unlikely", there it goes in the trash bag.

(Note: Does not apply to jewelry or photo albums. Does apply to inexpensive decoration).

It's not easy, and you have to learn to let go of things. But it made moving a lot easier, each time. I'm still doing the whole thing 1-2 times a year, and throw away a lot (although, with things that are still usable, I try to give them away for free via a facebook group).

Maybe you can try that on a small scale.