We should not think that we can progress in devotional service if we are mechanical. Bhakti cannot be generated by a mechanical process. Bhakti is eternal, which means that it has no beginning and no end. Therefore, as Rupa Goswami described in the verse above, "Such devotion eternally exists within the heart of every living entity." What will "awaken" that devotion? By coming in contact with bhakti in the heart of a devotee, "our" bhakti is awakened. What will increase that bhakti? Continued association with bhakti.
(Collected Letters to My Disciples, Vol 3, Pg 59, 2nd Paragraph)