I have a complicated relationship with discipline. I train BJJ, I publish every week, I meditate most days, and I still lose whole mornings to my phone if I pick it up before my brain is awake. So I do not collect discipline quotes because they are inspiring. I collect them because a memorised line, at the right moment, is sometimes the only thing standing between me and the worse decision.
That is how the Stoics used these lines too. Epictetus told his students to keep certain principles "at hand", procheiron, like a tool in a belt. The Enchiridion literally means "the thing held in the hand".
So here are fifteen lines worth holding. Pick one. Not five. Use it for a week before you come back for another. After each group I have added a note on how I actually use them, and the translations are linked to their public-domain sources so you can check every line.
Morning resolve
"In the morning when you rise unwillingly, remember: you rise to do the work of a human."
Marcus Aurelius, Meditations 5.1, after George Long (Internet Classics Archive)
"When you wake, say: the people I meet today may be meddling, ungrateful, arrogant..."
Marcus Aurelius, Meditations 2.1, abridged (Internet Classics Archive)
Marcus wrote both of these to himself, which is worth sitting with. The most powerful man alive still needed a written argument to get out of bed. The second one looks pessimistic until you try it: deciding before breakfast that someone will be rude to you today means the rudeness, when it comes, lands on a prepared surface. Most of my bad days started as unprepared surfaces.
Action over talk
"Never call yourself a philosopher; show it."
Epictetus, Enchiridion 46, after E. Carter (Internet Classics Archive)
"Men are disturbed not by things, but by the views they take of them."
Epictetus, Enchiridion 5 (Internet Classics Archive)
The practical move with Enchiridion 46: next time you are about to announce a new habit to someone, do the first rep of it instead. I have noticed the announcement and the rep draw from the same tank, and the announcement usually drains it.
Guarding attention
"Such as are your habitual thoughts, such will be the character of your mind; the soul is dyed by the thoughts."
Marcus Aurelius, Meditations 5.16 (Internet Classics Archive)
"To be everywhere is to be nowhere."
Seneca, Moral Letters 2 (Wikisource)
Seneca wrote that about reading too many books at once, which I find quietly funny given what we now do with browser tabs. The letter is two pages long and worth reading whole.
Obstacles as material
"Don't demand that things happen as you wish, but wish that they happen as they do happen, and you will go on well."
Epictetus, Enchiridion 8, tr. E. Carter (Internet Classics Archive)
"It is in your power never to act contrary to your daemon [better self]. No one can compel this."
Marcus Aurelius, Meditations, Book 8 (Internet Classics Archive)
When a plan collapses, the question I borrow from Epictetus is not "why did this happen" but "given this, what is the best use of me now". Same facts, different posture. The first question is an appeal. The second is a job.
Willing acceptance
"Lead me, Zeus, and you too, Destiny, wherever you have assigned me; I will follow. If I refuse, I'll be dragged."
Cleanthes, the Hymn fragment quoted in Enchiridion 53 and Seneca, Letters 107
"Accept everything which happens... it is fitted to you and woven with your destiny."
Marcus Aurelius, Meditations 5.8 (Internet Classics Archive)
The Cleanthes line is the oldest in this list and the bluntest statement of amor fati you will find: cooperate with what is happening or be dragged behind it. The cart goes either way.
Training the will
"Begin, therefore, from little things... say: 'This is the price of tranquillity. Nothing is free.'"
Epictetus, Enchiridion 12, after E. Carter (Internet Classics Archive)
"You may be unconquerable, if you enter into no contest that is not in your power to win."
Epictetus, Enchiridion 19 (Internet Classics Archive)
Musonius Rufus, Epictetus's own teacher, made the same point with less poetry. Virtue requires askesis, habitual training, and he prescribed voluntary hardship to get it: plain food, cold, heat, physical work. His Lectures and Fragments survive in the Cora Lutz translation if you want the source. The body, for Musonius, was where the will did its reps. Choose the simpler lunch, walk the last stop, carry the bag. Small frictions, deliberately taken, so the big ones do not break you.
"Our plans miscarry because they have no aim... when a man doesn't know what harbor he's making for, no wind is the right wind."
Seneca, Moral Letters 71.3 (Wikisource)
"The greatest remedy for anger is delay."
Seneca, On Anger 2.29, Maximum remedium irae mora est (Scaife Viewer)
That last one has saved me more arguments than any other sentence in this list. Anger writes the reply in seconds. Two minutes of delay and the reply is usually shorter, and sometimes it is nothing.
How I actually practise these
Not a system. Just what has survived contact with my own laziness.
In the morning, before the phone, I read one line aloud, usually Meditations 5.1 or 2.1, and write a single aim for the day on paper. That is Seneca's harbour. Without it, every wind feels urgent and none of them is right.
During the day, the work is mostly catching the moment between urge and action. Enchiridion 5 is the tool: name the thought behind the urge, then ask what is actually in my power right now. Some days I catch it twice. Some days zero. The catching itself is the discipline, and it improves like grip strength, slowly and only with use.
In the evening, three questions Seneca describes borrowing from Sextius: what did I do well, where did I fall short, what will I do differently. Two minutes. The honest version of this is uncomfortable, which is how you know it is working.
And once or twice a week, one voluntary discomfort, in the Musonius spirit. Anything you would not otherwise choose. The content matters less than the fact that you chose it.
A few common questions
What is Stoic discipline? Training the will to prefer the considered action over the impulsive one, by focusing on what you control, aiming at something definite each day, and rehearsing small hardships before life assigns you large ones.
Which Stoic is best on discipline? They cover different ground. Marcus for getting up and facing people, Epictetus for the moment of temptation, Seneca for planning and anger, Musonius for the body. If you are starting from zero, start with Enchiridion 5 and stay there a while.
How reliable are these translations? All linked to public-domain scholarly sources: MIT Internet Classics for Marcus and Epictetus, Wikisource for Seneca's letters, the Scaife Viewer for On Anger. Where a line is a modernised rendering rather than the translator's exact wording, the credit above says "after" the translator.
Most people treat discipline as a personality trait they either got or did not. The Stoics treated it as a practice, a thousand small rehearsals, most of them invisible. You do not need to overhaul your life tonight. You need one line you believe, and the next rep.
If you want a structure for the first week, the 7-Day Stoic Challenge is free: one audio lesson and one exercise a day. It is the rep, not the announcement.