Two beats: calm, then the deed. The passage is built as a coupling of two movements (τὸ πρῶτον… ἔπειτα — "first… next"). The first is a settling of the mind, DOGMA"be not troubled" (μὴ ταράσσου): the ground is double — cosmological (DOGMA"all is according to the nature of the Whole", πάντα κατὰ τὴν τοῦ ὅλου φύσιν) and memorial (EXERCISE"soon you will be nobody and nowhere"). Both dissolve anxiety: the event is lawful, and the one troubled by it is short-lived.
Hadrian and Augustus as the measure. The names are not chosen at random: the two most powerful principes, one of them the recent adoptive "grandfather" of Marcus himself. If they are already "nowhere," then the care for "how you will seem" (8.1) is emptier still. The transience of power is a standing motif (cf. Med. 8.31: the court of Augustus is gone; 4.33).
From contemplation to act. The second beat is EXERCISE"look into the matter" (ἀτενίσας εἰς τὸ πρᾶγμα): the gaze is not scattered but fixed on the task at hand. Then a threefold remembrance: TERM"you must be a good man", recall TERM"what man's nature requires" (τί ἡ φύσις ἀπαιτεῖ), and do it "without turning back" (ἀμεταστρεπτί). The closing triad of adverbs sets the quality of the act: εὐμενῶς (with goodwill), αἰδημόνως (with modesty-conscience), ἀνυποκρίτως (without play-acting). The strict terms by the word are φύσις and ἀγαθόν; αἰδημόνως is left unlinked to αἰδώς (an adverb of a different lexeme), and δικαιότατον to δικαιοσύνη. The governing discipline is action (to do the deed at hand), the sustaining one desire (not to be troubled at the order of the Whole).