To the man who only has a hammer everything he encounters begins to look like a nail.
* * *
To the stoic who only has virtue everything he encounters begins to look like an opportunity to exercise it.

On those mornings you struggle with getting up, keep this thought in mind - I am awakening to the work of a human being. Why then am I annoyed that I am going to do what I'm made for, the very things for which I was put into this world? Or was I made for this, to snuggle under the covers and keep warm? It's so pleasurable. Were you then made for pleasure? In short, to bo coddled or to exert yourself?

(Marcus Aurelius, Meditations, 5.1)

What any one may say or think of him, or do against him, on this he spends not a thought. He satisifies himself with these two things: With acting justly in what he is present doing; and with loving what is at present appointed to him. He has thrown off all hurry and bustle; and has no other will but this, to go on in the straight way according to the law; and to follow God in a straight way

(Meditations, X.11)

On ambition and success:

"Do you wish to win at Olympia? So do I, by the gods, for it is a fine thing. But consider the first steps to it, and the consequences, and so lay your hand to the work. You must submit to discipline, eat to order, touch no sweets, train under compulsion, at a fixed hour, in heat and cold, drink no cold water, nor wine, except by order; you must hand yourself over completely to your trainer as you would to a physician, and then when the contest comes you must risk getting hacked, and sometimes dislocate your hand, twist your ankle, swallow plenty of sand, sometimes get a flogging, and with all this suffer defeat.

When you have considered all this well, then enter on the athlete’s course, if you still wish it. If you act without thought you will be behaving like children, who one day play at wrestlers, another day at gladiators, now sound the trumpet, and next strut the stage. Like them you will be now an athlete, now a gladiator, then orator, then philosopher, but nothing with all your soul. Like an ape, you imitate every sight you see, and one thing after another takes your fancy. When you undertake a thing you do it casually and halfheartedly, instead of considering it and looking at it all round".

Enchiridion 29

If you're 25, this is how many weeks you have left (on average).

Always conduct yourself as though you are at a formal banquet. If the dish has not reached you yet, don’t be impatient. Wait your turn. When it comes around to you, reach out and take a modest amount. If it passes by you, don’t try to pull it back.
If you act the same gentle and restrained way with your spouse, children, wealth, and status, you will be entitled to dine with the gods. If you go a step further and decline even what is given to you, you will not only be in the company of gods, but share their powers as well.

Enchiridion, 15

On the Shortness of Life (Meditations 5:33)

Soon you’ll be ashes, or bones. A mere name, at most–and even that is just a sound, an echo. The things we want in life are empty, stale, and trivial. Dogs snarling at each other. Quarreling children–laughing and then bursting into tears a moment later. Trust, shame, justice, truth–gone from the earth and found only in heaven.

Why are you still here? Sensory objects are shifting and unstable; our senses dim and easily deceived; the soul itself a decoction of the blood; fame in a world like this is worthless.

–And so?

Wait for it patiently–annihilation or metamorphosis.

–And until that time comes–what?

Honor and revere the gods, treat human beings as they deserve, be tolerant with others and strict with yourself. Remember, nothing belongs to you but your flesh and blood–nothing else is under your control.

Today I escaped anxiety. Or no, I discarded it, because it was within me, in my own perceptions — not outside.

If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment.

(Marcus Aurelius)

"Let no-body have it in his power to say with truth of you, that you are not a man of simplicity, candour and goodness. But let him be mistaken, whoever has such an opinion of you. Now, all this is in your own power. For, what is he who hinders you to be good, and single-hearted? Only do you determine to live no longer if you are not to be such a man. For neither does reason, in that case, require you should."

- Marcus Aurelius, Meditations

"We suffer more often in imagination than in reality"
- Seneca

"Every man's life is sufficient. But yours is nearly finished, and still your soul reveres not itself, but seeks your well-being in the souls of others." - Marcus Aurelius

One of the most important and freeing principle of stoicism for me is to learn let go of others perceptions of you, and look into your own self for all the approval and love you seek

Don't confuse your thoughts of pain with pain itself.

Look closely and you will see your mind has a habit of complaining. Like a child throwing a tantrum, it cries out: "I am in pain!" "I am depressed!" "I feel sick!" "This is unbearable!"

Leave these thoughts unchecked and they will overpower you, drowning out your inner reason.

Therefore, in the midst of pain, remember your nature:
You are a philosopher.
This is the fabled arena, and the opponent is worthy.
This is your opportunity to inspire the crowd with courage and composure.

After all, philosophy is useless until used

It is my privilege to love even those who stumble. This love follows as soon as I reflect that they are like me, and they do wrong through ignorance; and above all they do me no harm, for they have not made my ruling faculty worse than it was before.
—Meditations 7.22