I’ll go first: “You have to have children when you’re young,” told to me when I was in my late 20s, with no desire to ever have kids, and no means to support them, by someone divorced multiple times with at least one adult child who does not speak to them.
Also: Responding to “How do I deal with this problem?” questions with “Oh, don’t worry about it, it’s enough that you’re even thinking about it!”
To me, it’s very zen. it’s more about putting the situation in the perspective that you need to handle the situation for what it is and not focus on being upset at the situation or being upset at not having a solution. Not every scenario has an end that works out for you, If you even have any control over it.
I usually hear it said when someone is having difficulty with a problem they have no real control over. Sometimes you just have to let things go and deal with your own emotions on the situation (which nobody else can do for you), or remove yourself from the situation entirely.