Lay down from this moment a certain character and pattern of behaviour for yourself, which you are to preserve both when you’re alone and when you’re with others.
Epictetus (c.50 – 135), Handbook (33.1)

Lay down from this moment a certain character and pattern of behaviour for yourself, which you are to preserve both when you’re alone and when you’re with others.
Epictetus (c.50 – 135), Handbook (33.1)

Men seek for seclusion in the wilderness, by the seashore, or in the mountains – a dream you have cherished only too fondly yourself. But such fancies are wholly unworthy of a philosopher, since at any moment you can choose to retire within yourself. Nowhere can man find a quieter or more untroubled retreat than in his own soul; above all, he who possesses resources in himself, which he need only contemplate to secure immediate ease of mind – the ease that is but another word for a well-ordered spirit. Avail yourself often, then, of this retirement, and so continually renew yourself.
Marcus Aurelius (AD 120 – 180), Meditations (4.3)

Give your heart to the trade you have learnt, and draw refreshment from it. Let the rest of your days be spent as one who has wholeheartedly committed his all to the gods, and is thenceforth no man’s master or slave.
Marcus Aurelius (AD 120 – 180), Meditations (4.31)

Leave another’s wrongdoing where it lies.
Marcus Aurelius (AD 120 – 180), Meditations (9.20)

All the things that fortune favours become fruitful and pleasant only if those who possess them are also in possession of themselves and not in the power of their property. It is a mistake to judge fortune responsible for anything that is good or bad for us. Fortune merely gives us the material for good and bad things—the preliminaries for what will turn out to be either good or bad within us.
Seneca (4 BC – AD 65), Moral Letters to Lucilius (98.2)

For the stone thrown there is no more evil in falling than there is goods in rising.
Marcus Aurelius (AD 120 – 180), Meditations (9.17)

Facts stand wholly outside our gates; they are what they are, and no more; they know nothing about themselves, and they pass no judgement upon themselves. What is it, then, that pronounces the judgement? Our own guide and ruler, Reason.
Marcus Aurelius (AD 120 – 180), Meditations (9.15)

Stoicism for the modern world, death to the self-help book industry, and a healthy scepticism towards social media.
Happy: Why more or less everything is absolutely fine by Derren Brown is superb. It’s beautifully written, wonderfully observed, both philosophical and practical (which once upon a time were one and the same thing). Very thought-provoking.

I think I first heard of Happy from a Donald Robertson interview and it treads similar ground to How to Think Like A Roman Emperor. However, it does so in a completely different way.
I particularly enjoyed Chapter 5, A (Very) Brief History of Happiness.
Thoroughly recommended.

He who lets the world, or his own portion of it, choose his plan of life for him, has no need of any other faculty than the ape-like one of imitation. He who chooses his plan for himself, employs all his faculties. … Human nature is not a machine to be built after a model, and set to do exactly the work prescribed for it, but a tree, which requires to grow and develop itself on all sides, according to the tendency of the inward forces which make it a living thing.
John Stuart Mill (1806 – 1873), On Liberty

All of us are creatures of a day; the rememberer and the remembered alike.
Marcus Aurelius (AD 120 – 180), Meditations (4.35)