For clothes, I have sorted depending on what I wear the most and if i haven't worn it for a year so I throw it or give it. Same for my horse, a saddle pad I haven't put in months I give it!
For the various category it's exactly all the small equipment I've been buying for years, old boots, brushes I have in 4 times...
For the sentimental things, I admit that I have not been able to throw any of my rosettes, even those I have in several times
I'm a fan of Marie Kondo's show on Netflix so I applied her method at my house and just recently in my tack room!
I applied her method and her rules for the barn: first take care of sorting the clothes (horse riding and "clothes" of my horse with saddle pads, blankets, boots...), various things, then books and papers (at the stable not much but a few paperwork to sort) and finally the sentimental objects (my first helmet, the whip with which I won a championship...).
To know if i keep something or not, you have to ask yourself " does it bring me joy?"
here are the rules:
RULE 01: Commit yourself to tidying up.
RULE 02: Imagine your ideal lifestyle.
RULE 03: Finish discarding first.
RULE 04: Tidy by category, not by location.
RULE 05: Follow the right order.
RULE 06: Ask yourself if it sparks joy.