In the name of God

Peace and mercy of Allah be upon you

One of the reasons why your mind is distracted for a moment which is likely to happen during the practice is that the pace of recitation goes up and down.

If during presenting your memorized verses, memorization, repetition or different practices which are given by teachers your pace of recitation goes up and down for any reason or you miss the recitation calmness you should look forward to be distracted from irrelevant things.
If you don’t want it to happen, you should be in the state of “Iqra”(reciting legibly) It means you should read perceptually, and you should do Iqra heartily as an imaginary listener while reading from memory.

It’s not right to think you’re really alone, even though you’re practicing or repeating the memorized verses by yourself. It’s essentially a bad thought.

Always your tone of speech should be like an oration with some emphases which may increase your concentration I mean; you gleam the verses upon your heart yourself and you read them in a perceptual manner.

This will affect your tone, your low-speed recitation and specially your mental control during recitation.
Unfortunately, some memorizers apparently attempt to read more verses or reach the end of Juz. And this is really wrong.

I mean if it’s so, then you won’t pay attention to the meanings any longer and you increase the pace of recitation only to reach your intended time or content.

And then, there is no reward for a recitation which doesn’t accompany the perception of the meanings it hasn’t much reward and it may be at the minimum of reward, and in addition, it will be faulty technically.

I mean you didn’t read it well-concentrated in technical manner look, it’s ten times more effective to memorize one Juz with good concentration, in right spirit, and with calmness and a smooth rhythm than to read only.

Yes, even when you practice lonely, feel it like Eqra and feel it like the realization and gleam the verses upon your heart in terms of meanings or to remind the images or in terms of those emphases which are needed according to verses meanings because some verses are epical and some others are like an oration or are interrogative and there are many different tones which are usable based on the verses meanings. And this may cause more stable memorization and better concentration and it’ll bring together all of existential things to enhance quality.

Good luck.