(Prabhupada's lecture - Śrīmad-Bhāgavatam 1.16.25 - Hawaii, January 21, 1974)
So if we actually want to be happy, then we should not live like animals, without any restriction, without any... Even in your state, just to keep proper management of the state, there are so many laws. Even you... As soon as you go on the street, you see there is state law immediately, "Keep to the right." Discipline must be there. That is dharma, discipline, to abide by the state laws. There must be some discipline. Similarly, to make yourself advanced in spiritual life, you must have to observe the discipline. Without discipline, it is not possible. Ādau gurvāśrayam.
Therefore Rūpa Gosvāmī says in his Bhakti-rasāmṛta-sindhu that discipline means, one who observes discipline, he is called disciple. Everyone knows it. Disciple means one who observes discipline. If one does not observe discipline, then he is not a disciple. And one who is not a disciple, his life is chaotic. He cannot be happy. Therefore Vedas say that "You must accept a bona fide guru and become disciplined under his instruction." Then you'll know the higher system of knowledge, the necessity of life, and thus you become happy.