Nothing, anymore.
After I got divorced ten years ago, I did a major purge, then an even bigger one about 4 years ago when I downsized. At least twice a year I go through and get rid of stuff, whether it be old cosmetics or clothing, if I haven't used it or looked at it in 6 months, BYE. I rarely regret getting rid of things, and most things can easily be replaced. I find clutter very stressful.