If you can do something about it, do not worry.
If you cannot do something about it, do not worry.
This quote comes in handy when my mind is wrangling things that cannot be changed/aren’t my desired outcome/are completely beyond my control. One of my new year’s resolutions (Chinese and otherwise) is to cut down on complaining at work (it’s hard–try it for yourselves!) or at the very least, avoid non-constructive complaining, i.e. try to come up with a solution, not just complain for the sake of complaining. Having said that, about two seconds after I announced my resolution to my colleague/friend N, I starting ranting about the ridiculousness of some recent office politics.
N: That’s not complaining, is it?
Me: No, it’s just me pointing out an objective fact.
N: (laughing) Just checking.
Oh, Buddha. Give me strength.