Distractions and Japa.

Distraction is referential. It is like weeds. What are weeds? They are what you do not want to grow. In the plant kingdom, there are no weeds. There are only different plants. You grow grass, and therefore anything other than that grass, even any other kind of grass is a weed. Suppose you care for your lawn and find a herb growing in it, what would you do? You would weed it out. Suppose you are growing the herb and you see grass around it obstructing its growth, then what would you do? You would weed grass out. Now tell me, which is the true weed? Anything you do not want is a weed, and you weed it out.

In chanting a mantra, you are giving yourself an occasion to check how your mind works. You are giving yourself an occupation which repeats itself. It becomes predictable. Any other thing becomes an unwanted distraction. When your mind moves away, pull yourself up. Bring it back from its wanderings to its assigned occupation of japa. This makes you learn the ways of your mind.

यतो यतो निश्चरति मनश्चलमस्थिरम्।
ततस्ततो नियम्यैतदात्मन्येव वशं नयेत्।।६.२६।। भगवद्गीता

For whatever reason the unsteady mind, always in a state of flux, goes away, bringing it back from that, with reference to the self alone, may one bring (the mind) into one's own hands.

The mind moves away, thinking of something else. This is expected. It is the nature of the mind to move away. Then bring it back from wherever it has gone and keep it on your chosen pursuit.