“Epictetus says we must discover the missing art of assent and pay special attention to the sphere of our impulses – that they are subject to reservation, to the common good, and that they are in proportion to actual worth.” Marcus Aurelius, Meditations.
To my mind, the second most important lesson from the Stoics, after differentiating that which is in your control from that which is not, is this from Epictetus. Whatever you are experiencing right now – be that positive or negative – ask yourself three questions: firstly, can I step back, park it, walk away from it, sleep on it for a while, rather than allow the emotions to play out unreservedly? Secondly, what good will come of acting on or perpetuating these emotions? Who or what will benefit, and who or what will suffer? And thirdly, in what proportion to the facts are these emotions, impulses and thoughts – in proportion or out-of-proportion?
Just taking the time to ask these three questions can take the steam out of the moment.