Find good limits. Seneca, Epistles 3.23.6

Beware of pleasures not because they must be bad, in themselves, but because they tempt you to forget limits. Limitation is necessary. We cannot afford to lose sight of it, in any place we inhabit. This is a significant problem with much naïve modern discourse about freedom (conceived as absence of limitation: while history shows many examples of evil straitjackets, bad limitation, it also warns that we require limitations, that omitting them entirely is at least as evil as having the wrong ones).

Fac, oro te, Lucili carissime, quod unum potest praestare felicem: dissice et conculca ista, quae extrinsecus splendent, quae tibi promittuntur ab alio vel ex alio; ad verum bonum specte, et de tuo gaude. Quid est autem hoc de tuo? Te ipso et tui optima parte. Corpusculum quoque, etiam si nihil fieri sine illo potest, magis necessariam rem crede quam magnam. Vanas suggerit voluptates, breves, paenitendas, ac nisi magna moderatione temperentur, in contrarium abituras. Ita dico: in praecipiti voluptas dolorem vergit, nisi modum tenuit.

Modum autem tenere in eo difficile est, quod bonum esse credideris.

Dearest Lucilius, I beg you to do the one thing that can keep you happy: cast off and trample underfoot all things that shine with borrowed splendor, everything promised to you by another or from another's store. Look to real happiness, and rejoice in what is your own. What is that? Whatever dwells in your person, and its best part. You should think of your body as something small and expedient here, rather than anything grand, even if nothing happens to you without it. The pleasures it recommends are empty, brief, and liable to demand repentance: if you neglect to check them frequently, with serious discipline, they will plunge you into torment. Mark my words: Pleasure is ever slipping headlong down the cliffs of pain, unless she finds some limit to hold her fast.

It is hard to keep a limit on something once you have deemed it good.