Of course some of us like more things around us than others, which is fine. But I believe William Morris said it best when he said "Have nothing in your house that you do not know to be useful or believe to be beautiful." And whether this
is your style, that pretty much says it all - although I would like to take it a step further.
First, make sure you find it beautiful or useful now. If the last time you used it was 3 years ago but you might use it again in another 3 years, it's not useful. If you loved the crystal vase when it was given to you at your wedding years ago but now your tastes are different, it's no longer beautiful to you.
Make sure when you look at something, you feel happy. Sentiment is neither useful nor beautiful. Keeping the photos of your honeymoon hanging on the wall now that you are divorced is not a good idea. Neither is keeping the still-beautiful-to-you lamp given to you by your ex-mother-in-law, who no longer speaks to you now that you're divorced. Unless of course all you see is the beauty of the lamp and feel no other emotions around it. (Be honest!)
And the best news? When you're done with loving it, there are probably plenty of people who will. Sell or give away* those things that still have life in them. Give someone else the opportunity to find them beautiful or useful.
*One of my favorite give-away places is Habitat for Humanity's ReStore. Not only do they take old furniture, accessories, building materials and things like old kitchen cabinets, but they pick up!