By Shrila Prabhupada
If one has enthusiasm in the beginning of devotional service, and that enthusiasm does not become cold, then one will never become apathetic, lazy, or distracted in chanting the holy names. Therefore enthusiasm is the only support for all types of devotional service. By enthusiastically performing devotional service one can give up anisthita service in a very short time and thus attain nistha. Therefore Srila Rupa Gosvami has said:
By the awakening of faith, one becomes eligible for devotional service. When this eligiblity is attained, one achieves the association of devotees. By the association of devotees, one is engaged in the execution of devotional service. In the beginning there is no nistha, or firm faith, in that service because various types of anarthas keep crushing the heart. All anarthas are vanquished, however, by performing devotional service with enthusiasm. The more anarthas are vanquished, the more nistha is awakened.
The word sraddha is certainly faith, but enthusiasm is the life of sraddha. Faith without enthusiasm is meaningless. Many people think they have faith in God, but because they have no enthusiasm, their faith has no meaning. Therefore, due to lack of sadhu-sanga, they do not perform devotional service.
There are six principles favorable to the execution of pure devotional service:
(1) utsaha, being enthusiastic;
(2) niscaya, endeavoring with confidence;
(3) dhairya, being patient;
(4) tat-tat-karma-pravartana, acting according to regulative principles [such as sravanam kirtanam visnoh smaranam-hearing, chanting and remembering Krsna];
(5) sanga-tyaga, abandoning the association of nondevotees; and
(6) sato vrtteh, or sadhu-vrtti, following in the footsteps of the previous acaryas.
These six principles undoubtedly assure the complete success of pure devotional service."