The Guru Mantra

Some time ago Sri Swami Vishwananda was explaining the meaning of a Guru Mantra.
Sri Swami Vishwananda: The word itself says it- Guru-mantra: a mantra, which has been given by the Guru. And when a guru gives a mantra to a person, there's also the grace of the Master into it.
When one chants the grace of the Master- the Master has already risen in spirituality, one receives also this part.
So, when a Guru gives you a Mantra and you chant this Mantra, you're also participating in the Divinity of the Master.
But you have to practice it!
It's like: you go to a doctor. The doctor will give you a medicine, but it's upon to you to drink it, no?
So, when you drink it- you will get well!
The same thing.
If you don't have a personal Guru Mantra yet, you can always chant 'Om Namo Narayanaya'- the Mantra for Lord Vishnu.
http://www.youtube.com/watch?v=aBy0nU2rPEY&feature=related