Stephen R. Covey, the author of the hugely popular The 7 Habits of Highly Effective People, suggests that we apply the Stoics principle as follows:
Imagine two circles. The outer circle is called the “circle of concerns,” which includes things that can cause us concern, but which we cannot really influence. The other circle is the "circle of influence," which includes things that we can influence, that we should take responsibility for. The more we focus our attention on the circle of influence, the more relaxed and effective we will be ”.
And finally, I would like to share with you an image that is very useful to me. We all have a hard time knowing which things we can change and which we cannot. We need to train ourselves, letting go of ballast, recognizing more and more easily what it is that I control and what I don't! To make it clearer and clearer intuitively, think about this:
When I look out to sea and see the waves come ashore...
Can i tell them to stop
I can not.
So when you are facing a complicated situation, ask yourself,
Is this like waves?