For those who have no taste for hearing and chanting, their only means of purification is to execute their duties according to varna and asrama, and gradually become elevated to the status of Vaishnava. But for those who have a taste for hearing and chanting, they get their inspiration and strength from the spiritual platform, and thus can accept whatever duties are prescribed for them and execute them as a matter of duty. The point is that they are not dependent upon the taste from the duty itself. They are getting both taste and strength from sadhana, and can remain steady in their duty because their life is nourished by something other than their duties.
The example is of Kholaveca Sridhar, who was satisfied selling plantain leaf cups and plates every day, even though it was not a very lucrative business. He lived in what appeared externally to be poverty. However, he was fully satisfied because he was absorbed in the holy name. He was neither constantly thinking of changing his job from one day to the next, nor was he thinking of renouncing his duty. He performed his work as a matter of duty, giving half of his earnings for the worship of Ganga devi, and was satisfied.
(Collected Letters to My Disciples, Vol 3, Pg 47, last Paragraph)