I think you should pack up the stuff you don't use and place them in a box out of sight and try going minimalist for a while (6 months?). If you have a change of heart, you can go back and reopen that box. If you don't, then you won't feel bad about selling those items.
I've done this. The problem is that I keep having to fill another box. And another, and another...
Seriously, I'm up to two shoeboxes full.