Within Stoic philosophy from Ancient Greece, the teachings of a central figure named Epictetus are compiled in the Enchiridion, a short handbook on how to live according to these values. You can compare the major translations here. This post just adapts some of the guidelines to be clearer and easier to reference for my own personal reflections. It is not a translation of the original text, which, by the way, is way more inspiring than my notes here, and includes bars like:
"If any instance of pain or pleasure, glory or disgrace, be set before you, remember that now is the combat, now the Olympiad comes on, nor can it be put off; and that by one failure and defeat honor may be lost - or won."

Valley of the Creuse, Claude Monet
- There are things within your power, and things beyond your power. Within your power are your thoughts, choices, and aims, which are by nature free, as no one else can control these things. Beyond your power are things like health, possessions, and status, that you are never guaranteed to have because they are dependent upon other people or circumstances. If you try to control these things in life, you will only be discouraged when you fail. Instead, you should focus only on improving what is fully yours, which is your will. In life you are constantly faced with impressions of the world, and you want to make a judgment of each impression that is in harmony with its nature, that is, if it's something in your power or not. A lot of things may appear to be in your power that actually are not. And if anything is beyond your power you must be able to say it doesn't matter to you.
- When you want something, you attach your happiness to the outcome of getting it, and the same goes for when you don’t want something, to the outcome of avoiding it. If you want to avoid illness, for example, you will be unhappy because it's beyond your power to avoid that. But if you want to avoid making bad choices, it is in your power to do so. You can never be discouraged if you only try to avoid the bad things that you have the power to bring upon (and therefore take away from) yourself.
- Everything is temporary by nature, even the closest people in your life.
- Before you do something, think about what could go wrong by the nature of that thing and how you want to keep your will in harmony with the world rather than fight against what you can’t control. If things do go wrong, you’ll already be in the mindset that it was going to happen anyway, and you had prepared for it.
- When something upsets you, often it’s not the thing itself but the judgments you make of it. You shouldn't blame others or even yourself for what upsets you, only your judgments.
- Only take pride in things that you make of your own will.
- Be prepared that life may suddenly take you away from what you love.
- Don’t hope for anything to happen the way you want it to, but hope for it to happen as it will naturally happen, and you won't be discouraged (see #4).
- Things like illness and injury don't hurt the mind, only something else, like the body. This is the case for most things, unless you let them.
- When you are overwhelmed by some impression of the world, look inside yourself and ask what faculty or mental strength you have to deal with it.
- Since you never own anything except your will, you can never really lose anything either, even people. You could think of losing something as giving it back to the world instead.
- Don't give other people power over your peace of mind if they won't do what you want or agree with you. You'll have to let things go if you want to keep your will in harmony with the world, as in, you can't control other people.
- To go down the path of improving your mind and your judgments, you will have to let go of the need to be considered important by others.
- Whoever controls the things you want and the things you want to avoid is the one who controls you. So if you want to be completely free, you have to make that person be yourself and only yourself. (See #2 and #12.)
- Practice restraint when you want something.
- When you see someone grieving, it's important to remember (as in #5) that it is not what happened that hurts them but rather their judgment of that thing as bad. Obviously, this doesn't exempt you from going to comfort the person, but reminds you not to forget that what is beyond your power cannot harm you unless you let it (see #9).
- Life may cast you in many roles and you should play each one with dignity, even when the role is one of suffering.
- Don’t be discouraged by bad news, all news is good because you can make use of it in some way.
- When you see someone with power, money, or status, don't believe the impression that they are happy. They are not free, because they have attached their happiness to things beyond their power (see #2). "You can be unconquerable, if you enter into no combat in which it is not in your own power to conquer."
- When someone provokes you, you are not upset by their words, but by your choice to judge them as bad or harmful (see #5 and #9). If you keep this in mind and practice it often, then you will be able to keep your will in harmony with the world, that is, not feel harmed by things beyond your power. Instead of confronting the person saying these things, you can choose to confront your own judgment and how it has let you down. You might even feel encouraged by how well you have responded to the impression.
- Always keep in your mind the perspectives in #3 and #7, that everything is temporary and can be lost in a matter of moments, even your own life.
- People won't care when you tell them that you're trying to improve yourself and that's fine. They will come to admire you by your actions, not your words.
- Don't try to convince others that you're improving yourself, convince yourself first. The moment you turn your attention to things that are beyond your power, like the validation of others, you undo all the work you've done.
- The fear of being nobody important in life is not one you should worry about. It is no business of yours to pursue power or status or recognition, because you will lose what is good and makes you truly honorable, which is your will. "How is it true that you will be nobody anywhere, when you ought to be somebody in those things only which are within your own power, in which you may be of the greatest consequence?"
- Everything beyond your power, especially the pursuit of power, requires an exchange that will take away something good in yourself. You could become someone seen as important in life but you will have to trade part of your will to other people and circumstances, and open yourself to suffering. Remember that power is just an impression (see #19).
- (see #16)
More to come