Bhakti-rasamrta-sindhu (1.2.2) gives the following information about sadhana-bhakti:

The process of devotional service-beginning with chanting and hearing-is called sadhana-bhakti. This includes the regulative principles that are intended to awaken one to devotional service. Devotional service is always dormant in everyone's heart, and by the offenseless chanting of the holy names of the Lord, one's original dormant Krsna consciousness is awakened. This awakening to Krsna consciousness is the beginning of sadhana-bhakti. This can be divided into many different parts, including faith, association with devotees, initiation by the spiritual master, engagement in devotional service under the instructions of a spiritual master, steadiness in devotional service and the awakening of a taste for devotional service. In this way, one can become attached to Krsna and His service, and when this attachment is intensified, it results in ecstatic love for Krsna. The word rati is explained in the Bhakti-rasamrta-sindhu (1.3.41) as follows:

"When a tenderness of the heart is manifest, there is rati, or attachment. Those who are interested in being liberated from material bondage must manifest this tenderness called rati." This attachment is not like material attachment. When one is liberated from material contamination, the awakening of attachment for Krsna's service is called rati. In the material world there is attachment for material enjoyment, but this is not rati. Transcendental rati can be awakened only on the spiritual platform. Ecstatic love for Krsna (prema) is described in the Bhakti-rasamrta-sindhu (1.41) as follows:

"When the heart is completely softened and devoid of all material desires and when one's emotional feelings become very strong, one becomes very much attached to Krsna. Such purified emotion is known as pure love."