Men seek retreats for themselves - in the country, by the sea, in the hills - and you yourself are particularly prone to this yearning. But all this is quite unphilosophic, when it is open to you, at any time you want, to retreat into yourself. No retreat offers someone more quiet and relaxation than that into his own mind, especially if he can dip into thoughts there which put him at immediate and complete ease: and by ease I simply mean a well-ordered life. So constantly give yourself this retreat, and renew yourself. The doctrines you will visit there should be few and fundamental, sufficient at one meeting to wash away all your pain and send you back free of resentment at what you must rejoin.
And what is it you will resent? Human wickedness? Recall the conclusion that rational creatures are born for each other's sake, that tolerance is a part of justice, that wrongdoing is not deliberate. Consider the number of people who spent their lives in enmity, suspicion, hatred, outright war, and were then laid out for burial or reduced to ashes. Stop, then. Or will you fret at your allocation from the Whole? Revisit the alternatives providence or atoms - and the many indications that the universe is a kind of community. But will matters of the flesh still have their hold on you? Consider that the mind, once it has abstracted itself and come to know its own defining power, has no contact with the movement of the bodily spirit, be that smooth or troubled: and finally remember all that you have heard and agreed about pain and pleasure.
Well then, will a little fame distract you? Look at the speed of universal oblivion, the gulf of immeasurable time both before and after, the vacuity of applause, the indiscriminate fickleness of your apparent supporters, the tiny room in which all this is confined. The whole earth is a mere point in space: what a minute cranny within this is your own habitation, and how many and what sort will sing your praises here!
Finally, then, remember this retreat into your own little territory within yourself. Above all, no agonies, no tensions. Be your own master, and look at things as a man, as a human being, as a citizen, as a mortal creature. And here are two of the most immediately useful thoughts you will dip into. First that things cannot touch the mind: they are external and inert; anxieties can only come from your internal judgement. Second, that all these things you see will change almost as you look at them, and then will be no more. Constantly bring to mind all that you yourself have already seen changed. The universe is change: life is judgement.
The great passage from Meditations is Book 4.3. In this, Marcus lays out all that is needed for your Inner Citadel.
People experience anxiety and stress from work and the busyness of life. They think they need an escape or vacation. People will drown their cares in alcohol or eating or drugs or time away from work - a week in Europe or in the mountains or on a white-sand blue-water beach, or at Disney World. They seek to "get away from it all". Marcus tells them and us, that if you want this reprieve, it is already there in your mind. A quick trip to your mind, a re-cap of your doctrines and
voila, you are ready to rejoin society. And you can do this anytime; no need to schedule your escape.
Next he tells us how to quickly revisit those doctrines. Do you hate, resent, are frustrated with, are bothered by or are disgusted with someone? Remind yourself that rational beings are meant for each other (discipline of action). Work with the other person; have compassion and understanding towards others. Most likely, they are not acting out of mal-intent. And what if they were acting with malice? That is out of your control. Either the other person is acting in accordance with the universe or they are acting randomly. If they are acting in accordance with the universe, accept it. If not, then don't you act badly or randomly - an ordered life is a content life.
Does fame (or lack of it) bother you? Soon you and all those who you would want to cheer you on will be gone. This world a speck in the vast universe. This lifetime a blip on the infinite. Fame is pointless.
Lastly, the two "most immediately useful thoughts" you should have while in your Inner Citadel are:
1) Peoples' opinions, actions, world events, elections, wars, natural disasters - they cannot touch the mind. All the good or bad you place on these externals come from your mind. It is your attitude that determines if things or good or bad or indifferent (discipline of assent).
2) Change is constant - the universe is change and life is all about how you view it (attitude / judgement). At the very least, if you don't like something, eventually it or you will change. Accept this constant; accept what the universe doles out to you and everyone else; accept your lot in life (discipline of desire).
(see
Citadel p. 38-42, 53, 55, 105, 147, 149, 176, 265, 291)