Have you heard of ClutterFreeBox? It's a service that stores your stuff by the box (rather than by the storage unit). You can just fill up boxes with your clutter, ship them off (for a fee) and have the company store them (for a monthly fee per box). Need the stuff back? They're happy to ship it to you, again, for a fee.
This is a great money-maker for ClutterFreeBox, but do you really want to pay and pay to store items you probably don't actually need to own?
Declutter and you won't need services like these.