Count it all joy. Marcus Aurelius 3.4.3-4
Mind your own business, and make it your aim to receive all gifts of fortune with gratitude. This is a hard struggle, a contest that we do not easily win.
ὁ γάρ τοι ἀνὴρ ὁ τοιοῦτος, οὐκέτι ὑπερτιθέμενος τὸ ὡς ἐν ἀρίστοις ἤδη εἶναι, ἱερεύς τίς ἐστι καὶ ὑπουργὸς θεῶν, χρώμενος καὶ τῷ ἔνδον ἱδρυμένῳ αὐτῷ, ὃ παρέχεται τὸν ἄνθρωπον ἄχραντον ἡδονῶν, ἄτρωτον ὑπὸ παντὸς πόνου, πάσης ὕβρεως ἀνέπαφον, πάσης ἀναίσθητον πονηρίας, ἀθλητὴν ἄθλου τοῦ μεγίστου, τοῦ ὑπὸ μηδενὸς πάθους καταβληθῆναι, δικαιοσύνῃ βεβαμμένον εἰς βάθος, ἀσπαζόμενον μὲν ἐξ ὅλης τῆς ψυχῆς τὰ συμβαίνοντα καὶ ἀπονεμόμενα πάντα, μὴ πολλάκις δὲ μηδὲ χωρὶς μεγάλης καὶ κοινωφελοῦς ἀνάγκης φανταζόμενον τί ποτε ἄλλος λέγει ἢ πράσσει ἢ διανοεῖται. μόνα γὰρ τὰ ἑαυτοῦ πρὸς ἐνέργειαν † ἔχει καὶ τὰ ἑαυτῷ ἐκ τῶν ὅλων συγκλωθόμενα διηνεκῶς ἐννοεῖ κἀκεῖνα μὲν καλὰ παρέχεται, ταῦτα δὲ ἀγαθὰ εἶναι πέπεισται· ἡ γὰρ ἑκάστῳ νεμομένη μοῖρα συνεμφέρεταί τε καὶ συνεμφέρει. μέμνηται δὲ καὶ ὅτι συγγενὲς πᾶν τὸ λογικόν, καὶ ὅτι κήδεσθαι μὲν πάντων ἀνθρώπων κατὰ τὴν τοῦ ἀνθρώπου φύσιν ἐστί, δόξης δὲ οὐχὶ τῆς παρὰ πάντων ἀνθεκτέον, ἀλλὰ τῶν ὁμολογουμένως τῇ φύσει βιούντων μόνων. οἱ δὲ μὴ οὕτως βιοῦντες ὁποῖοί τινες οἴκοι τε καὶ ἔξω τῆς οἰκίας καὶ νύκτωρ καὶ μεθ᾽ ἡμέραν, οἷοι μεθ᾽ οἵων φύρονται, μεμνημένος διατελεῖ. οὐ τοίνυν οὐδὲ τὸν παρὰ τῶν τοιούτων ἔπαινον ἐν λόγῳ τίθεται, οἵγε οὐδὲ αὐτοὶ ἑαυτοῖς ἀρέσκονται.
The man who achieves this, refusing to put himself beyond the limits already found by our best people, becomes a worthy priest and worshiper of the gods. Making good use of the indwelling faculty that renders humanity impervious to pleasures, invulnerable to toil, untouched by outrage, indifferent to every hardship, he enters the lists of our greatest contest: the struggle against passion. When justice turns against him, drowning him in her depths, still he greets every event victorious with joy, welcoming all comers, caring little what another says or does or thinks, unless some weighty responsibility binds him to that person. He administers only his own affairs, and consistently regards these as tightly woven into the fabric of the universe: as all nature's affairs are beautiful, he is convinced that his cannot help being good. The fate allotted to each of us is borne with us and bears us along with it, in his mind. He remembers that every rational faculty is kin to him, and that while it is part of human nature to worry about all people, he must not cling to every opinion: the only thought he grasps after comes from folk living in harmony with nature. Nor does he forget the attitudes of those living contrary to nature, what discontent they have at home and abroad, by night and by day, in every sort of company. He does not think it rational to value the praise of people who do not even please themselves.
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† Editors have marked this passage as corrupt. I am not sure I agree.