If you want to motivate yourself to get rid of clutter...

... calculate what you're paying to store it.

[I]f you live in a 1,500-square-foot house and have a $1,500 monthly payment, that's obviously $1 per square foot per month. Now multiply by how many square feet are devoted to storage. This can be an eye-opening experience. Let's say you've let an entire room slowly drift into a "junk" room even though it was originally intended as a guest bedroom or a sewing room. You've got 100 square feet or more devoted to storage in that one room alone. So you're paying 100 x $1 = $100 a month for the privilege of having a junk room....

Count all the shelf, closet, and drawer space too. Put a dollar amount on what you pay a month to keep the stuff you've got there. That's the rent that stuff should be paying. Is it worth that much to you? If not, why won't you evict it?