It can be a brutal process. But so freeing! In the last year, I've cleaned out one drawer, one shelf, one area (more or less) a day. I lost track of the bags and boxes of stuff I've donated. Truth is, I don't miss any of it. Heck, I don't even remember most of it. Doing it a little at a time, but every day, worked well for me. Once a week trips to the charity shop, so I couldn't change my mind. We're staying put, so I don't need to technically downsize, but getting rid of the clutter has been great.