Sri Chaitanya Mahaprabhu has taught us in Shikshashtaka, 4th verse,

na dhanam na janam na sundarim
kavitam va jagad-isa kamaye,
mama janmani janmanisvare
bhavatad bhaktir ahaituki tvayi

What are we to desire from God? Chaitanya Mahaprabhu is teaching us. If there be any worldly motive in performing bhajan, we will get that but we will be deprived from getting eternal welfare. We should not have any ulterior desire in our mind while performing bhajan.

Chaitanya Mahaprabhu has taught us in the above verse that we should not want wealth, manpower, worldly learning or even emancipation. We should only pray to the Supreme Lord Sri Krishna to bestow on us one-pointed exclusive devotion to Him. The first attainment of performing harinam sankirtan is purification of the mind. We are not to perform yogic meditation for cleansing our minds, but nam sankirtan should be done in the company of bona fide sadhus - shudha bhaktas. The second attainment of performing harinam sankirtan is the extinguishment of the forest fire of the cycle of birth and death and threefold afflictions. The third attainment is eternal welfare, i.e. the appearance of the Supreme Lord, Who is All-good. Harinam is the life of Spiritual learning - paravidya vadhu.

There are two kinds of learnings: one is material learning and another is spiritual learning, realisation of one’s relationship with the Supreme Lord, as eternally connected to Him as His servant. After that, with that relationship, when one chants the Name, he will be immersed in the ocean of bliss and then, at every step he will have the taste of transcendental ambrosia and lastly, there will be complete purification of the body, mind and soul.