We've had a hard time getting rid of stuff. We bought our house from my in-laws, who were downsizing to a one-bedroom condo. We moved in as they were moving out, and a few months later we realized that they had stopped taking stuff. Their new place was full, so they just started stashing stuff in our garage, basement and attic.
My MIL has always been a pack rat, and a lot of it stems from growing up in the Philippines during WWII, when people had very little of anything.
A few weeks ago, I decided to clear some attic space so that I could put my weight bench and rollers (for the bicycle) up there. I donated two carloads of clothes, filled the recycling and trash cans two weeks straight, and can finally move around up there without falling over stuff.
i also went thru the stuff in the basement and filled another recycling can full of old papers (from various associations they belonged to over the years).
I think after the holidays I'll start on the basement again. There's a pool table I want to get rid of, plus the Lenox collection (MIL's) that I've hidden down there (we had vases all over the house when we moved in), and some boxes of LPs and other stuff that I need to look at. I even found a box of 8-track tapes down there.
I've been a pack rat myself when it comes to books. I must have at least 5,000 books in the attic. It might be worth trying to sell them online, but we'll see. If it's more trouble than it's worth, they'll end up at Goodwill.