Commentary on Meditations: B11:16-17

Live through life in the best way you can. The power to do so is in a man's own soul, if he is indifferent to things indifferent. And he will be indifferent if he looks at these things both as a whole and analysed into their parts, and remembers that none of them imposes a judgement of itself or forces itself on us. The things themselves are inert: it is we who procreate judgements about them and, as it were, imprint them on our minds - but there is no need for imprinting at all, and any accidental print can immediately be erased. Remember too that our attention to these things can only last a little while, and then life will be at an end. And what, anyway, is the difficulty in them? If they are in accord with nature, welcome them and you will find them easy. If they are contrary to nature, look for what accords with your own nature and go straight for that, even if it brings you no glory. Anyone can be forgiven for seeking his own proper good.

With each object of experience consider its origin, its constituents, what it is changing into, what it will be when changed and that no harm will come to it.

Stoic indifferents are things over which people have no control.  When we speak of indifferents, we are talking about our health, wealth and possessions, our fame, our avoidance of pain, seeking pleasure and anything outside of our control.  We have no ultimate control over these things.  What we can control regarding indifferents is our attitude toward them.  We can be indifferent to indifferents.  These indifferents have no ability to bust open our mental door to our brain and force us to think and act in a certain way.  Rather, it is us who allow our minds to be swayed by these things.  I can look at all the things that happened in the year 2017 (snake bite, death in family, heart operation, home flooding) and I could allow these things to determine my happiness.  Or not ... I could focus on exercising virtue and the discipline of assent and in a sense, create a story to turn these obstacles into valuable lessons.  I hope I have striven and succeeded at the latter.  Ultimately, this life is short, and it will all be over soon and none of this will really matter anyway.

The discipline of assent helps us to be indifferent to things indifferent.  Analyze everything and each experience; break things apart, think of where it came from, how it changes and what it will turn into.  Regarding everything, ask yourself if you have control over it.  This question, more than anything else, greatly reduces anxiety and mental stress because it cuts out so many possible decisions and choices.  It cuts through to the heart of the matter.

(see also Citadel p. 41, 71, 108, 272)