Updated Dec 24, 2017
If it is really a “need” then that means a survival issue.
For example, I need some clothing, to protect my temperature, modesty, social-acceptability, and ability to get a job.
I have a fairly small number of “just-in-case” items, which I haven’t used in some time. Some are just extra computer cables, and things on that level.
I have had a mental adjustment in going paperless. It is just an adjustment, and I was OK, after the initial strange sensation.
Although, with the paperless issue, I still have a stack of textbooks. Not a huge stack (I could lift it up with both hands). Regular biology and chemistry books, that would be used for university, or then reasonably just keep on your shelf for quick reference. I love books and paper.
I have a few documents of legal and medical nature, with physical paper copies that I haven’t needed in a long time (when was the last time you had to show a certified birth certificate?). This stack is less than a centimeter thick, but it would be a major hassle to replace things like my passport, which I actually need.
On a sentimental level, I have a sweatshirt with a certain design, which was a gift from a long-time friend. I think that is the only sentimental item, and I actually wear it on a regular basis.
A couple of physical scrolls from university qualifications.
One thing I do is look to the past versus now. Of my possessions, the only things that I have from twenty years ago, are that small stack of documents. Everything else has cycled into new stuff.
Lastly, I have an inventory system where I place a designation about relocating. Some things I would relocate across town. Some things I would relocate to another city or country. Each physical item has its designation, and, for the local-move-only items, I would toss them without hesitation, if I were to relocate a long distance by bus/train/plane.