In all your actions, words, and thoughts, be aware that it is possible that you may depart from life at any time. But leaving the human race is nothing to be afraid of, if the gods exist; they would not involve you in anything bad. And if they do not exist or have no concern for human affairs, why should I live in a universe empty of gods and empty of providence? But the gods do exist and have concern for human affairs and have placed it wholly in the power of human beings never to meet what is truly bad.

[Ὡς ἤδη δυνατοῦ ὄντος ἐξιέναι τοῦ βίου, οὕτως ἕκαστα ποιεῖν καὶ λέγειν καὶ διανοεῖσθαι. τὸ δὲ ἐξ ἀνθρώπων ἀπελθεῖν, εἰ μὲν θεοὶ εἰσίν, οὐδὲν δεινόν: κακῷ γάρ σε οὐκ ἂν περιβάλοιεν: εἰ δὲ ἤτοι οὐκ εἰσὶν ἢ οὐ μέλει αὐτοῖς τῶν ἀνθρωπείων, τί μοι ζῆν ἐν κόσμῳ κενῷ θεῶν ἢ προνοίας κενῷ; ἀλλὰ καὶ εἰσὶ καὶ μέλει αὐτοῖς τῶν ἀνθρωπείων καὶ τοῖς μὲν κατ̓ ἀλήθειαν κακοῖς ἵνα μὴ περιπίπτῃ ὁ ἄνθρωπος, ἐπ̓ αὐτῷ τὸ πᾶν ἔθεντο.]

Marcus Aurelius (AD 121-180) Roman emperor (161-180), Stoic philosopher

Meditations, Book 2, #11 [tr. Gill (2014)]
    (Source)

Original Greek. Alternate translations:

Whatsoever thou dost affect, whatsoever thou dost project, so do, and so project all, as one who, for aught thou knowest, may at this very present depart out of this life. And as for death, if there be any gods, it is no grievous thing to leave the society of men. The gods will do thee no hurt, thou mayest be sure. But if it be so that there be no gods, or that they take no care of the world, why should I desire to live in a world void of gods, and of all divine providence? But gods there be certainly, and they take care for the world; and as for those things which be truly evil, as vice and. wickedness, such things they have put in a man's own power, that he might avoid them if he would.
[tr. Casaubon (1634), #8]

Manage all your Actions and Thoughts in such a Manner as if you were just going to step into the Grave. And what great matter is the Business of Dying; if the Gods are in Being you can suffer nothing, for they'll do you no Harm, and if they are not, or take no Care of us Mortals, why then I must tell you, that a World without either Gods, or Providence is not worth a Man's while to live in. But there's no need of this Supposition; The Being of the Gods, and their Concern in Human Affairs is beyond Dispute. And as an Instance of this, They have put it in his Power not to fall into any Calamity properly so called.
[tr. Collier (1701)]

Since it is possible that thou mayest depart from life this very moment, regulate every act and thought accordingly. But to go away from among men, if there are gods, is not a thing to be afraid of, for the gods will not involve thee in evil; but if indeed they do not exist, or if they have no concern about human affairs, what is it to me to live in a universe devoid of gods or devoid of providence? But in truth they do exist, and they do care for human things, and they have put all the means in man's power to enable him not to fall into real evils.
[tr. Long (1873 ed.)]

Manage all your actions, words, and thoughts accordingly , since you may at any moment quit life. And what great matter is the business of dying? If the gods are in being, you can suffer nothing, for they will do you no har. And if they are not, or take no care of us mortals -- why, then a world without either gods or Providence is not worth a man's while ot live in. But, in truth, the being of the gods, and their concern in human affairs, is beyond dispute. And they have put it entirely in a man's power not to fall into any calamity properly so-called.
[tr. Zimmern (1887)]

Whatever you do or say or think, it is in your power, remember, to take leave of life. In departing from this world, if indeed there are gods, there is nothing to be afraid of; for gods will not let you fall into evil. But if there are no gods, or if they do not concern themsleves with men, why live on in a world devoid of gods, or devoid of providence? But there do exist gods, who do concern themselves with men. And they have put it wholly in the power of man not to fall into any true evil.
[tr. Rendall (1898 ed.)]

Let thine every deed and word and thought be those of a man who can depart from life this moment.[16] But to go away from among men, if there are Gods, is nothing dreadful ; for they would not involve thee in evil. But if indeed there are no Gods, or if they do not concern themselves with the affairs of men, what boots it for me to live in a Universe where there are no Gods, where Providence is not? Nay, but there are Gods, and they do concern themselves with human things;[17] and they have put it wholly in man's power not to fall into evils that are truly such.
[tr. Haines (1916)]

In the conviction that it is possible you may depart from life at once, act and speak and think in every case accordingly. But to leave the company of men is nothing to fear, if gods exist; for they would not involve you in ill. If, however, they do not exist or if they take no care for man's affairs, why should I go on living in a world void of gods, or void of providence? But they do exist, and they do care for men's lives, and they have put it entirely in a man's power not to fall into real ills.
[tr. Farquharson (1944)]

In all you do or say or think, recollect that at any time the power of withdrawal from life is in your hands. If gods exist, you have nothing to fear in taking leave of mankind, for they will not let you come to harm. But if there are no gods, or if they have no concern with mortal affairs, what is life to me, in a world devoid of gods or devoid of Providence? Gods, however, do exist, and do concern themselves with the world of men. They have given us full power not to fall into any of the absolute evils.
[tr. Staniforth (1964)]

You could leave life right now. Let that determine what you do and say and think. If the gods exist, then to abandon human beings is not frightening; the gods would never subject you to harm. And if they don't exist, or don't care what happens to us, what would be the point of living in a world without gods or Providence? But they do exist, they do care what happens to us, and everything a person needs to avoid real harm they have placed within him.
[tr. Hays (2003)]

Do, say, and think each thing as if it is possible to die right now. To leave the discussion of human affairs, if there are gods, it is nothing terrible -- for they would not ensnare you in evil. If, moreover, there are no gods -- or if the realms of men are not their concern -- why would I live in a universe emptied of gods or their foresight? No, there are gods and they are concerned with the affairs of men. And they have completely arranged it that the human race many not fall into evils that are truly evil.
[tr. @sentantiq (2017)]