The Serenity Prayer asks you to understand what is within and what is outside your control.
There is a similarity to the Stoic philosophers’ view of this point. From a comment on r/stoicism:
[T]here is a deeper meaning, specific to Stoicism, which is not obvious and not easy. The things within your control are your reason and your will, and that’s it. Not your body, not your knowledge or your skills or your family or friends or possessions. Just your reason, and your will.
Look at something and decide what it is and how it effects you. Choose what to do. Nobody else can steer that, or prevent you from doing it. We can reason with you, persuade you, and maybe you’ll agree, and maybe not. It’s you, your core self. It’s the only thing you need to worry about, the only thing you need to get right, and everything else follows from that.
Your mind, your attitude. This is the only thing to put in the “control” category. Everything else? That lives in acceptance territory. It’s something you cannot change.
Another comment in the same thread puts it succinctly:
Basically the only thing we have under our control is our choices. Circumstances, externals, results, others, etc are all considered out of our control.
Emphasis in original.
Another thread on r/stoicism talks about control as seen by Epictitus, in the context of politics:
Things that are “outside of your control,” in the sense that Epictetus is talking about in the dichotomy of control, are those things that are not fully and completely in your control. They are things that are external to the will. (You can’t just will it and make it happen.) Epictetus gives the examples of your body, your wealth, and your reputation, since all of these things depend on outside forces.
Things that are “in your control” are those things dependent solely on your will. No forces outside of your willpower can stop them from happening. They are opinion, choice, and desire/aversion, and they are commonly referred to as the Three Disciplines.
So in the Stoic sense, it doesn’t matter whether or not you are in a position of political power, you will never have (complete) control over policies or anything else external to the will. But your intention to try to make the world a better place is within your control.
It’s tricky sometimes, because there is the appearance of control. I push a button on my coffeemaker and I get coffee. I mash my right foot down in my car and it goes fast.
But do I really control the car or the coffeemaker? Only in a superficial way. These machines can — and will — break. There is nothing I can do to prevent that.
I talk and ask or persuade someone to do something. Am I in control? Not at all. That person may have done what I wanted. But that does not mean I have control.
So remember that. Courage to change — on my own thoughts, attitudes, beliefs, actions. Acceptance — everything else.
That’s what the old guys told me.
With that clear line, it’s pretty easy to know what to do. And if you’re confused, think about where to draw the line — that will clarify things, pronto.