If by the tongue you chant Hare Krishna mantra and by the tongue you taste prasadam, you will be perfect, simply by executing these two things. Do not accept anything, do not allow the tongue to touch anything which is not offered to Krishna. This is one item.Another item — engage the tongue always in chanting Hare Krishna. You become perfect.
Lecture on Bhagavad-gita 1.10 — London, July 12, 1973
One must read Srimad Bhagavatam regularly and with scrutiny to gradually become attached to the chanting of the Hare Krishna maha mantra.
Purport on Chaitanya Caritamrta Adi Lila 7.73
One may cleanse himself daily by taking a bath in water, but if one takes a bath even once in the sacred Ganges water of Bhagavad-gita, for him the dirt of material life is altogether vanquished.
Bhakti is a sort of cultivation. As soon as we say “cultivation”, we must refer to activity. Cultivation of spirituality does not mean sitting down idly for meditation, as some pseudo-yogis teach. Such idle meditation may be good for those who have no information of devotional service and for this reason it is sometimes recommended as a way to check distracting materialistic activities.