स तु दीर्घकालनैरन्तर्यसत्कारासेवितो दृढभूमिः ॥

sa tu dīrghakālanairantaryasatkārāsevito dṛḍhabhūmiḥ

It becomes firmly grounded by long constant efforts with great love (for the end to be attained).

In plain words: Practice becomes strong only through long, steady effort done with real love for the goal. Self-control does not come in a day.