Are you an influencer or are you always being influenced? Do you act or are you always being acted upon? Are you a player or an NPC?
These are the kinds of questions Epictetus is driving at in this chapter. He wants you to be an influencer in life. He wants you to act. He wants you to be the player in the game.
Therefore, he offers some sound advice for developing good, strong habits.
If you want to make progress as a Stoic, you will have to be cautious about who you associate with. Either you will become more like them or they will become more like you. If your soul is at risk of becoming more like them (non-Stoic), then be cautious.
"Someone who associated regularly with certain people, for conversation, or for parties, or simply for the sake of socialability, is bound either to come to resemble them or else to convert them to his own way of life" (v. 1, p. 173).
"Until these fine [Stoic] thoughts are firmly established in you, and you've acquired the power that is needed to guarantee your safety, I would advise you to be cautious about getting involved with laymen" (v. 9, p. 173).
If you're a recovering alcoholic, ought you to associate with people who go to the bar all the time? No!
As such, we are all recovering blathering idiots and we need to educate ourselves with philosophy. During this time, be cautious not to associate with people who think the National Enquirer and Entertainment Tonight are the best thing since sliced bread!
"You should retire to some place far away from the sun, as long as your [philosophical] opinions are like wax. That is the reason why philosophers recommend that we should even leave our homeland, because old habits distract us and hold us back from making a start on developing new ones" (v. 10-11, p. 174).
You "should introduce new habits in place of your old ones; fix your ideas firmly within you, and exercise yourselves in them" (v. 13, p. 174).
Constantly ask yourself, "How do I deal with these impressions that present themselves to me? In accordance with nature or contrary to it? How shall I respond to them? In accordance with nature or contrary to it? Do I declare to those things that lie outside the sphere of choice that they mean nothing to me?" (v. 15-16, p. 174)