When you are thinking about what to get rid of, you can just ask yourself:
How much would it cost to get it replaced?
If one day, you think you MIGHT need the item, think about what it would cost you to replace it to put things into perspective.
When you are about to clean out something from your closet, let’s say a really nice fancy winter coat that was originally $1600 that you aren’t sure you want to keep because you’ve lost weight and it’s too big on you… think about whether or not you’d want to buy that exact coat again.
If keeping a $1600 coat makes you feel better because you think you MIGHT go up a size one day, perhaps it is worth it.
(Actually for $1600 you can probably consign the coat and get some of the money back, which makes the sting of having to get rid of it easier to bear.)
In contrast, if you are trying to get rid of an old grimy, paint-stained t-shirt you used to paint the entire house with that was $10, it is a much easier decision to get rid of that old $10 t-shirt and buy another one in the future if you decide you need another t-shirt to ruin.