We have contact with the physical body, so to execute prescribed activities and to help us experience a higher taste, we have to know how to dovetail our senses in the Lord's service. Srila Rupa Goswami defines sadhana-bhakti as devotional service rendered with the senses. Thus a sadhaka uses the ears to hear about Krishna, the tongue to chant about Krishna, the eyes to look at Krishna's deity form, and the nose to smell the flowers and tulasi leaves offered to Krishna.
Lectures from a Disciple, Vol. 2, The Process for Awakening Bhakti