Japa will eventually bring spiritual realization.
Do not give up Japa even if the mind is unwilling and unsteady. You must go on with the repetition. And you will find that the mind is getting gradually steadier – like a flame in a windless corner. Any movement in the air disturbs the steady burning of the flame; even so the presence of any thought or desire makes the mind unsteady. The Mantra must be correctly repeated. An incorrect utterance delays progress.
A single utterance of Lord’s name is as effective as a million repetitions of it, if only you do it with a steady, concentrated mind. What is the use of repeating a million times with an absent mind? You must do this whole-heartedly. Then only can you deserve His Grace.