How often is it that you find your concentration lapsing either in personal devotions or in public worship? Once, a few times or even perhaps much of the time? The most helpful book on this subject is 'A Remedy for Wandering
Thought in the Worship of God' written by the Puritan Richard Steele (recently it has been reprinted by Sprinkle Publications). The following is an abridged extract in slightly updated language from that book. The passage deals with the problem of distraction and the vital duty of watchfulness in every individual part (or ordinance) of worship. Steele calls watchfulness the perpetual or most continual duty of a Christian: this is the garment we must put on every day, in every duty.
Watching in worship
What is the first step in an ordinance? Watchfulness. What is the second step in an ordinance? Watchfulness. The third step? Still watchfulness.
In Prayer
Prayer is a pouring out of the heart unto the Lord; by a distraction you pour it aside. 'My soul, wait thou only upon God; for my expectation is from him' Psalm 62:5. A distraction imposes two masters on the soul to wait on. Rovings in prayer make that which is our most reasonable service the most irrational thing in the world. There is nothing more foolish than speaking to one person while thinking of another.
In hearing God's Word
This is the audible address of the Almighty to your soul. A distraction lets him talk unto the walls. When you come to a sermon, you 'stand on your watch, and set yourself on the tower, and watch to see what God will say to you' Habakkuk 2:1. By a distraction, you are doing almost the same as a servant who stops his ears at the orders that his master is giving.
In reading
In the Scriptures you peruse God's heart in black and white, where you may believe every letter to be written in bleeding love. A distraction neither understands nor applies those sacred letters. Would you read your father's last will in this way, especially in matters that concerned yourself? One chapter, one page, one verse, well read and applied will do your heart more good than a hundred read with half a heart.
In singing psalms
You need to watch in the singing of the psalms. By this ordinance you pay to God the rent of his mercies. With a distraction it is as though the payment is made with a counterfeit coin because it turns the heart to do homage unto the Devil. David had the best resolution: 'Bless the Lord. O my soul, and all that is within me praise his holy name' (Psalm 103: 1). Your melody is debased if the main strength of your soul is not in it.
I am persuaded that God has allowed this ordinance in particular to be slurred again and again, to be neglected by some and rejected by others out of his just judgement because there is such a widespread disregard for doing it with felt, inward grace. Where is the worshipper who actually lets each word and line in the psalms run through their heart as they sing them? The truth is that hardly one passage is felt from the beginning to the end, because if it were what heavenly affection it would produce and leave upon the soul! If you felt something of this you would not part with this ordinance for all the world in either your families or congregations.
In meditation
Here you must watch, or else when the soul is soaring aloft, like the eagle, before you are even aware these darts will strike down the heart again. How hard it is to spend even a quarter of an hour in meditation without a distraction! If there is anything in the imagination or memory, anything in the room, if there is anything in the world, you will have it in withdrawing your heart from God. As a rule, the more spiritual the duty, the more distractions.
The permanent habit of Watchfulness
You can be safe nowhere without watchfulness, at all times, in all places, with all companies, even with no company at all, in all callings: there is a snare for the heart everywhere. 'Wait on thy God continually' (Hosea 12:6) 'Be thou in the fear of the Lord all the day long' (Proverbs 23:17), especially but not only in your morning and evening sacrifices.
Many praying people are extremely devout and serious in God's service morning and evening, but follow them all day long and hardly one word of God or heaven is in their mouths, as though religion were hemmed up in times of worship. Be in the fear of the Lord, involved, surrounded and swallowed up in the sense and fear of God's glorious presence all the daylong. This will put you in the right spirit for duties of worship. A watchful Christian has his heart ready and on call. It is easily put into tune when it was never out of tune. Holy duties are not unwelcome to a holy heart. A short preface or none at all is sufficient in approaching him with whom you have been conversing all the day. Sometimes, however, the whole work of a prayer is in making God's acquaintance.