In the preliminary phase of spiritual life there are different kinds of austerities, penances and similar processes for attaining self-realization. However, even if an executor of these processes is without any material desire, he still cannot achieve devotional service.
Rareness of pure devotional service
In the Caitanya-caritāmṛta (Madhya 19.151) it is said, “By the mercy of the spiritual master who is a pure devotee and by the mercy of Krishna one can achieve the platform of devotional service. There is no other way.”
In Śrīmad-Bhāgavatam it is also confirmed by Prahlāda Mahārāja that merely by personal efforts or by the instructions of higher authorities one cannot attain to the stage of devotional service. One must become blessed by the dust of the lotus feet of a pure devotee, who is completely freed from the contamination of material desires.
In the Fifth Canto of Śrīmad-Bhāgavatam, Sixth Chapter, verse 18, Nārada also says to Yudhiṣṭhira, “My dear king, it is Lord Krishna, known as Mukunda, who is the eternal protector of the Pāṇḍavas and the Yadus… He is very dear and affectionate, and He is the director of all your activities, both individual and familial.
And what’s more, He sometimes carries out your orders as if He were your messenger! My dear king, how very fortunate you are, because for others all these favors given to you by the Supreme Lord would not even be dreamt of.” The purport to this verse is that the Lord easily offers liberation, but He rarely agrees to offer a soul devotional service, because by devotional service the Lord Himself becomes purchased by the devotee. http://iskconbirmingham.org