God, grant me the serenity to accept the things I cannot change the courage to change the things I can and the wisdom to know the difference.
Living one day at a time, enjoying one moment at a time.
Accepting hardships as the pathway to peace.
Taking, as he did, the sinful world as it is, not as I would have it.
Trusting that he will make all things right if I surrender to His will; that I may be reasonably happy in this life, and supremely happy with Him forever.
—Reinhold Niebuhr, 1892-1971
I've been in therapy many years, and you wouldn't believe how often it comes up and we discuss it in the context of some problem in my life. So much of life's difficulties hinge on the axis of trying to figure out where we can place our agency and where we should.
My preferred version: do what you can, don't sweat it.
To phrase it negatively, it's a kind of selfishness / indifference. But it's not "I don't care", but more "it is what it is".
I see some people accept with serenity the things that cannot be changed, but then have no courage to change the things which should be changed because they have no wisdom to distinguish the one from the other.
An easy read that dives into stoicism, a similar mindset, within the context of running the Roman Empire.
Great read.