A person who is always absorbed in Kṛṣṇa consciousness is called a devotee of Kṛṣṇa. Śrīla Rūpa Gosvāmī says that all the transcendental qualities discussed previously are also found in the devotees of Kṛṣṇa. The devotees of Kṛṣṇa can be classified into two groups: those who are cultivating devotional service in order to enter into the transcendental kingdom and those who are already in the perfectional stage of devotional service.
A person who has attained the stage of attraction for Kṛṣṇa and who is not freed from the material impasse, but who has qualified himself to enter into the kingdom of God, is called sādhaka. Sādhaka means one who is cultivating devotion in Kṛṣṇa consciousness. The description of such a devotee is found in the Eleventh Canto, Second Chapter, verse 46, of Śrīmad-Bhāgavatam. It is said there that a person who has unflinching faith in and love for the Personality of Godhead, who is in friendship with devotees of Kṛṣṇa, and who is very merciful to the ignorant, raising them to the standard of devotional service, and who is uninterested in nondevotees, is considered to be situated in the position of cultivating devotional service.
When one is found shedding tears by hearing of the pastimes of the Lord, it is to be understood that the blazing fire of material existence will be extinguished by such watering. When there is shivering of the body and the hairs of the body stand up, it is to be understood that the devotee is nearing perfection. An example of a sādhaka cultivating devotional service is Bilvamaṅgala Ṭhākura.
(Nectar of Devotion).

The Vedic culture is actual civilization, varṇāśrama-dharma. That is the beginning of civilization. Without Vedic culture and varṇāśrama-dharma it is animal civilization. When Rāmānanda Rāya and Caitanya Mahāprabhu was talking, Caitanya Mahāprabhu inquired from Rāmānanda Rāya, "What is the beginning of life?" Sādhya-sādhana."What is the object, objective of the ultimate goal of life, and how that objective of life is attained?" Sādhya-sādhyana. Sādhya means the objective thing, andsādhana means the process. Sādhya-sādhana. So Rāmānanda Rāya, he said, varṇāśrama. Varṇāśrama. That is the beginning of life. Because varṇāśrama means... The life is... Human life is meant for understanding the Supreme Lord. That is human life. The cats' and dogs' life is not meant for understanding God; it is not possible either. They cannot understand.
(Lecture on Srimad Bhagavatam----5:6:4).

Śrīla Rūpa Gosvāmī states in Bhakti-rasāmṛta-sindhu (1.2.295):
sevā sādhaka-rūpeṇa
siddha-rūpeṇa cātra hi
tad-bhāva-lipsunā kāryā
vraja-lokānusārataḥ
"In the transcendental realm of Vraja (Vraja-dhāma) one should serve the Supreme Lord, Śrī Kṛṣṇa, with a feeling similar to that of His associates, and one should place himself under the direct guidance of a particular associate of Kṛṣṇa and should follow in his footsteps. This method is applicable both in the stage of sādhana (spiritual practices executed while in the stage of bondage) and in the stage of sādhya (God realization), when one is a siddha-puruṣa, or a spiritually perfect soul."
(Nectar of Instruction).