Most people have several reasons why they keep stuff they do not need.
"It might come in handy some day." Sure, if you keep it long enough, but by then it'll be obsolete, out of style, not up to current code or simply too ugly. Unless you live in a Sam's Club Warehouse, when you have to think up a reason to keep something, it is a sure sign you don't need it.
"They sure don't make 'em like this anymore." Right, because it's obsolete, out of style or simply too ugly. If you can't use it, it should go. If you have to ponder an application for an object, get rid of it.
"But it reminds me of junior-year spring break." Sentimental value is often a barrier to shedding useless objects. But think it through. Do you really need another T-shirt, beer mug or a stolen street sign? Your memories exist separately from the items. The same holds true for the lamp from Aunt Wilhelmina. She's not a genie. She does not live inside the lamp. You really don't have to keep the lamp to love her. And if you hate the lamp, does keeping it really honor her?
"To let this go, I have to give something up." Perhaps one of the strongest reasons to keep something is the difficulty of letting go. If I send those size-4 jeans to Salvation Army, I am admitting that I will never be a size-4 again. That's hard. That idea holds for the books on the solar-energy, owner-built home. If I give them away, I am letting go of a fantasy I've held since high school. When letting go, accept the truth. Admit it, accept it, forgive yourself (if necessary), and then move on.
Your de-cluttered life will thank you.
How to De-clutter
1. Obtain six large boxes
2. Label them Return, Repair/Hem, etc., Give away, Garbage, Keep and Maybe.
3. Select one defined area to address such as a closet or drawer—not a whole room or "garage."
4. Pick up each object and put it in one of the six boxes.
5. Go to "maybe" box and sort into other five boxes.
6. Clean the area and then place items in a pleasing way.
Hint: If your "Maybe" box fills up first, you might need to re-read.