Long story involving travel, illness, caring for aging parents, and building a house, and we ended up with several years' worth of clutter. We had planned on hiring a rolloff container this summer to get rid of the clutter. A failed sump pump last week hastened the process. Our basement was a computer graveyard (among other things) and we found a recycler to take all the components off our hands. We lost a lot of "stuff' but during the process, we are learning that it's just stuff. TBH, I would say that we are minor hoarders, so we set rules for ourselves regarding what to keep and what to throw. For me, awards, achievements, etc. in paper (except for diplomas and transcripts), unless professionally mounted, get tossed. Saving all photographs, CDs, hard books, and art supplies that didn't get ruined. If we haven't worn it or used it in over a year, it goes.
In order to maintain the neatness, we plan on decluttering annually and handling every piece of mail as it comes in. I think for us, over the past however many years, we've just been unable to decide what to keep and what to toss and a job so large has been overwhelming. One of the things that bothers me is the sheer amount of junk mail that comes in. I am estimating that for every legitimate piece of mail that comes in (1 or 2 bills that can't be done electronically, and a few trade magazines), we receive 20 pieces of junk mail. I get credit offers from Capital One at least once a week (and if they can afford to waste that much paper, I don't think I want to deal with them anyway).
As of last night, I have been through every box in my house, and thrown away (or freecycled) a great deal of clutter.