It is the aspiration of a devotee that while he chants the Hare Krsna maha-mantra his eyes will fill with tears, his voice falter and his heart throb. These are good signs in chanting the holy name of the Lord.
Purport on Chaitanya Caritamrta Adi Lila 7.81
By performing congregational chanting of Hare Krishna mantra, one can destroy the sinful condition of material existence, purify the unclean heart and awaken all varieties of devotional service.
Men become strong and stout by eating sufficient grains, but the devotee who simply eats ordinary grains but does not taste the transcendental pastimes of Lord Chaitanya Mahaprabhu and Krishna gradually becomes weak and falls down from the transcendental position.
All kinds of activities, both auspicious and inauspicious, that are detrimental to the discharge of transcendental loving service to Lord Sri Kishna are actions of the darkness of ignorance.