This morning during Japa I had to deliberately take the focus away from my mind – it's an effort to do that but it requires strength and determination to switch back to the mantra.
I found the easiest way to achieve this was to keep reminding myself "Just listen to the sound of the mantra" and I repeated this over and over again. It took some time but after a few recitations, the noise of my mind dissolved and once again the sound of the mantra was all pervasive.
Please try this technique to overcome your mind during Japa.
Keep Reminding Yourself