Recently I've begun doing a little thought experiment: When is something "my problem" and when is it "not my problem?"
Everyone is a little different in this department, but personally, I tend to want to fix most problems I encounter, especially if that problem might adversely impact my life or a loved one's life.
Parenting, for example, feels like a process of slowly detaching myself from my children's problems and trying to give them the tools they need to solve their own problems themselves. They need that, because they're children.
It's a harder question, though, when it comes to other adults. When is another adult's problem actually my problem? More and more, I'm reaching the conclusion that the answer to that question is, unequivocally: "hardly ever."
I suppose it depends somewhat on the adult's role in my life, whether personal or professional, but despite differing impacts on me depending on the nature of the relationship, I'm starting to realize that problems originating with other adults are hardly ever actually my problem either to fix and/or accept accountability for.
Recently I confronted four unrelated situations on both ends of the spectrum that reaffirmed this for me. In the first two, two grownups (to whom I'm not related with whom I'm not even friendly) had fucked something up beyond repair, and it was objectively their fault. In the other two, people I'm close with were not acting in their own self-interest quickly enough or assertively enough (in my opinion).
When I stepped back from each of these situations and examined my impulse to fix them, I was able to see that they weren't really my problems to fix in the first place. These were adults who had made their own proverbial beds; there was nothing I could do to unmake them. Maybe everything would work out fine for them and maybe it wouldn't, but either way, it simply wasn't up to me.
I felt almost triumphant telling myself in no uncertain terms: "it's not your problem," and really believing it at a gut level. In a way this sounds selfish and mean, but really it's the opposite. Accepting that you can hardly ever "fix" someone else's problems for them is the ultimate relinquishment of narcissism and endorsement of another adult's autonomy.
In short, it feels good and grounding to say "it's not my problem," and mean it. I highly recommend it.