Custodian as in guardian, steward, keeper. Of what you may well ask. Of other people's stuff!
This is one of the sneakiest yet effective ways some purge. They pass their extra possessions on to you under the guise of a gift. Aha! Now maybe you are seeing some of your items for what they really are.
Take for example the tea towels that belonged to grandma, the huge dining room set from the 50's that was your aunt's wedding gift (and not your favourite aunt I might add), the old passports or costume jewellery of yesteryear. How did it end up at your place, taking up your living space, becoming part of your legacy?
Some of it you may actually love, like or use. Other items may have ended up at your house in your care in more subtle ways. Again, guilt by default - our culture's go to emotion that bears a lot of responsibility for our reactions. Italicized because there is a clear distinction between action and reaction. We have the choice.
Another friend or well meaning relative thought this item was so 'you'. It's part of a set. You may only use one piece of the set or a few but the complete 50 pieces take up 2 shelves of your limited cupboard space. Another classic - Person X passed it on to me and they thought it was so cute - so in homage to the cuteness - they gave it to YOU!! All very well meaning and kind but bottom line - now you have to find space for it. Why? Because otherwise you'll feel bad and you feel it is expected of you. After all, you have become the keeper.
Okay, enough. Now we have uncovered the hows and whys to our dilemma. What are we going to do about it? Mentally separate yourself from the object for the sake of this exercise. Put it in the middle of the room, on the floor or table. If you saw it in a shop window or at a friend's place would it be a show stopper? Would you walk on by, maybe appreciating it for what it is but not necessarily feel the need to acquire it. Or is it something you would think about in the following days and regret not having?
Here is a trick I have used many times. It came about when we were moving from France to Canada. We were very limited as to space for shipping our possessions due to expense so we really had to make judicious choices. During my initial sort there were things I felt were non negotiable, of course I would ship them. But alas, money has a cruel way of slamming you back down to earth.
So then as the purge and sort continued I started putting a lone item that I felt I couldn't live without in the middle of the floor in the main (only) hallway in our flat. Every time we had to go to another room, we had to walk around it or over it - tres annoying. But it quickly helped me discover just how much or not this item meant to me. I left it there for at least a day. If I was truly attached to it, I found a safe place for it so as not to damage it. If after seeing it over and over in the middle of the space it just got on my nerves I would realize that it could go. You get sick of inconvenience very quickly so you are spurred on to reduce the aggravation. If the object only served to irritate me after walking around if a few times then I knew I could live without it and still have a fulfilling existence.
Of course, this strategy worked for me and I still continue to do it sometimes even though we are not moving. You may do well to think about it and adapt it to your setting.
Consider the original owner of the item(s). Wherever they are now or whenever you are reunited with them - do you think this object will be the first thing you talk about? or the first thing they ask about? or will it ever even come up? I seriously doubt it. If it does though, if your relationship is worth its salt, it won't matter.
You were meant for greater things. A custodian of other people's random possessions will never be worth it.