Sometimes when our students of the Krsna consciousness movement chant and dance, even in India people are astonished to see how these foreigners have learned to chant and dance in this ecstatic fashion. As explained by Caitanya Mahaprabhu, however, actually this is not due to practice, for without extra endeavor these symptoms become manifest in anyone who sincerely chants the Hare Krsna maha-mantra.

From Srila Prabhupada's purport to Cc Adi 7.83