This morning I was reading from the Forth Canto of the Srimad Bhagavatam about the process of mantra meditation. I have always loved this story of Druva Maharaja, and his determination in meditation, on the form of the Lord. We have included the entire text and purport.
O son of the King, now I shall speak unto you the mantra which is to be chanted with this process of meditation. One who carefully chants this mantra for seven nights can see the perfect human beings flying in the sky. (SB4.8.53)
…Another point established in this verse is that meditation should be carried on with the chanting of a mantra. Chanting of the Hare Kṛṣṇa mantra is the easiest process of meditation in this age. As soon as one chants the Hare Kṛṣṇa mantra, he sees the forms of Kṛṣṇa, Rāma and Their energies, and that is the perfect stage of trance. One should not artificially try to see the form of the Lord while chanting Hare Kṛṣṇa, but when the chanting is performed offenselessly the Lord will automatically reveal Himself to the view of the chanter. The chanter, therefore, has to concentrate on hearing the vibration, and without extra endeavor on his part, the Lord will automatically appear.