I'm a natural minimalist, but the one thing that used to always trip me up were books and shoes - if I saw either that I wanted I was buying it. The shoes were (mostly) consistently re-used, but after one or two reads the books just sat on the shelf. A waste!
Plus, I hate feeling cramped so having too many things lying around makes me itch. So here's what I did:
a) Went through all the books in my house and immediately boxed the many I hadn't read in years. If I still hesitated, I only kept the book if it served me today. Everything went to the local shelter or library.
b) Got a library card and subscribed to Audible: The library now carries audio and e-books, which you can borrow via your phone. If a title isn't available you'll be placed on a waiting list. I borrow fiction and biographies and purchase/download non-fiction. I haven't bought a hardcopy book in years.
c) Shoes: if they hurt they were out. Period. Also given away or sold were any I hadn't worn in more than three years. With the remaining I made sure they were visible so I wouldn't buy a similar pair. This has worked wonders, and I don't miss any I've let go.
d) Clothes: Legitimate issue: my weight fluctuates. The last time I gave clothes away because they no longer fit I needed the same size again a few years later. But it was years, not days or weeks! I had to let that excuse go as well. I now give myself 18 months with the new weight and, if nothing changes, give away or sell ill-fitting items. I've also learned to buy a lot of stretchable material that can expand or contract along with me.
e) Misc items: I use reusable bags instead of plastic grocery bags; I constantly monitor my house for things I'm no longer using, then without deliberation place them in the donations bag. I constantly turn down tchotchkes and other small giveaways unless I genuinely need or know I'll use them; and I've either canceled magazine subscriptions entirely or switched to digital. The only one I still receive in hard copy is given to a friend as soon as it's been read.
I admit there are times when I miss something I've given away. But that rarely occurs, and I feel better with less clutter. Plus, there's a tax write-off on the donated items and the immediate benefit of selling something on Poshmark (eBay and Tradesy are great as well, I just haven't used them). If you hesitate to part with any of your things, use Marie Kondo's (Author: The Life-Changing Magic of Tidying Up) suggestion and only keep that which brings you true joy. You may find that most items are nice to have, comfortable, and/or may recall fond memories - but they don't currently bring you joy. Focus on your joy, and give someone else the opportunity to experience their own joy with items that no longer serve you.
And so it is.