Mantra - How it works

Mantra is a Sanskrit word.
It is a combination of two words - Man and Tra.

Man means mind - and Tra means to overcome - subdue, control, tame, or discipline.
So the Mantra, by definition, is by which one can control and train the mind.
According to Sages and Holy Scriptures, Sumiran - repeating a Mantra or a phrase over and over is the best way to tame the mind.

It's a known fact that the mind cannot do two things at the same time.
Although, we can train our body and the senses to do certain things with auto-memory by practicing it.
We do not have to pay much attention to perform many routine actions - such as cooking, cleaning, driving or jogging, etc. Our mind could be thinking of hundred other things while doing these habitual things that we are so used to doing every day. 

Once we have perfected it, some professional works - like weaving, sewing, farming, or operating small harmless machines, etc. can be done automatically - without much guidance from the mind.
We can listen to music, talk to friends over the phone, or think about other things, and yet, our body can keep working almost like a machine.

But the mental work - like serious mathematical calculations and accounting - solving an intricate problem or a puzzle, performing a complex musical composition in an orchestra - requires undivided concentration on the task at hand. One distraction or even a single unrelated thought for a second can become the cause of a big mistake.
Because the mind cannot be in two places.

And this is precisely how the Mantra works.

If we concentrate on a Mantra, the mind cannot wander around.
If it does, then it means the mind is not on the Mantra or the Sumiran.
Because it can only be in one place

We can train our tongue to keep repeating the Mantra while the mind is wandering somewhere else.
But that will defy the whole purpose of the Mantra or Sumiran - which is to control the mind - not to train the senses*.

Although we should try to focus on the name of Nirankar, Almighty God - while doing the daily routine work. 

But practically, doing Sumiran 24/7 with total concentration is not possible. Especially while doing some serious mental work.

Therefore, we should set aside or find some time for the concentrated Sumiran - by focusing only on Nirankar**.
                                              ‘Rajan Sachdeva’

*Maala to kar me phiray - Jeebh phiray mukh maanhi

Manuaa to deha dis phiray - yeh to Sumiran naahin      

                                    (Sant Guru Kabeer ji)

**Hari ka naam japahu sant meet

Saavdhaan ekaagra cheet 

                             (Gurbani)