The discipline of action in pure form. The passage is almost a textbook formula of Stoic action. Three beats: (1) persuade (πείθειν) — the preferred way; (2) but act even against their will (πρᾶττε ἀκόντων) when the "reason of TERMjustice" (ὁ τῆς δικαιοσύνης λόγος) so leads: others' unwillingness does not annul the duty; (3) if you are resisted by force (βίᾳ), switch. The governing discipline is action, the sustaining one assent (the inner acceptance of the outcome).
The obstacle as material. Under force — "pass to contentment and freedom from distress" (τὸ εὐάρεστον καὶ ἄλυπον) and "use the hindrance for another virtue" (συγχρῶ εἰς ἄλλην ἀρετὴν τῇ κωλύσει). The obstacle does not wreck the virtuous act but converts it into another virtue: where justice-in-deed is impossible, patience, mildness, tranquility are possible. Cf. 06-08 (the ruling part turns the hindrance into material for the deed).
The reserve-clause (ὑπεξαίρεσις). The heart is TERM"with a reservation" (μεθ’ ὑπεξαιρέσεως): every TERMimpulse (ὁρμή) toward an external end is made under the condition "if nothing prevents." Hence "DOGMAyou were not reaching for the impossible" (τῶν ἀδυνάτων οὐκ ὠρέγου). And the final turn: what were you after? — "an TERMimpulse of just this kind." And that you always attain, for it is in your power. The result may fail, but the rightly aimed effort has already been made: "the things toward which we were moved do come to pass."
Parallels. The TERMreserve-clause — Med. 4.1 (the mind adapts itself "with a reservation"); 5.20 (the hindrance to the deed becomes the deed); 8.41; 11.37; the DOGMAdichotomy of control; TERMimpulse under reservation — 06-27. The hindrance → another virtue — 05-20.