"[Once, in a village, a young boy was bitten by a snake. His parents were heart-broken. They wept bitterly. The whole village came over to see what had happened. Then someone said he will call a snake charmer who is expert in mantras.
Soon the snake charmer came. He kept reciting a mantra. He also put some stones on the boy's head, on his eyes and other important areas of the boy's body as only known to the snake charmer.
After much recitation of the mantra, the snake which bit the boy came. It sucked out all the poison from the boy's body. The snake then died. And the boy was saved.]
If a worldly mantra can have so much power, just imagine what the maha-mantra can do.
Hare Rama Hare Rama
This is the top most mantra. If anyone has taken shelter of a bona-fide guru, and following all of Sri Guru's instruction, then the disciple will see the results quickly. Meaning he will feel peace and bliss. He will not be disturbed by the material calamities.
The maha-mantra has been infused by Sri Guru's powers when He initiated the disciple. It is now the duty of the disciple to follow all the instructions of Sri Guru strictly.
Also, when Srila Gurudeva was exhibiting his "sick pastimes" there was a time when he needed to be operated on. The doctors administered anaesthesia. Usually a patient will be asked to count 1 to 10 and then he or she dozes of. Their counting will be get weaker and weaker.
But Srila Gurudeva was chanting the maha-mantra. And each time it only got stronger and stronger. All the doctors were amazed. They realized that Srila Gurudeva was not an ordinary person. Somehow or other the operation did take place. As for the doctors, the paid obeisances to Srila Gurudeva everyday!
You should never think that the maha-mantra Sri Guru gave you in an ordinary sense."