I will tell you as best I can what I do personally when I pray. May our dear Lord grant to you and to everybody to do it better than I! Amen.
First, when I feel that I have become cool and indifferent in prayer because of other tasks or thoughts (for the flesh and the devil always oppose and hinder prayer), I take my little prayer book, hurry to my room... and as time permits, I say quietly to myself, word-for-word, like a child, the Ten Commandments and the Creed. If I have extra time I also add some words of Christ or of Paul, or some psalms.
It is a good thing to let prayer be the first business of the morning and the last at night. Guard yourself against those false and deceitful thoughts which tell you, “Wait a little bit. I will pray in a hour; first I must attend to this or that.” Such thoughts get you away from prayer and off to other things which keep your attention until the day is gone and you have not yet prayed.... Thus we become lax and lazy, cool and listless toward prayer. The devil who haunts us is not lazy or careless, however, and our flesh is all too ready and eager to sin and resists the spirit of prayer.
When you have “warmed up” with the recitation [of the Ten Commandments and the Creed, etc.] and are intent upon the business at hand, then kneel or stand with your hands folded, look toward heaven and say or think this little prayer:
“Heavenly Father, dear God, I am a poor unworthy sinner. I do not deserve to lift up my hands and eyes to you in prayer. But because you have commanded us to pray and have promised to hear us and through your dear Son Jesus Christ have even taught us exactly how and what to pray, I come to you in obedience to your word, trusting in your gracious promise. Together with all your saints and Christians on earth I now pray in the name of my Lord Jesus Christ as He has taught us: Our Father who are in heaven, etc., (through the whole Lord’s Prayer, word for word).”
Then repeat one part or as much as you wish, perhaps the first petition, “Hallowed be Thy name,” and then say something like: “Yes, Lord God, dear Father, hallowed be Thy name, both in us and throughout the whole world.... Convert those who are still to be converted what they with us and we with them may hallow and praise your name, both with true and pure doctrine and with a good and holy life. Amen.”
Perhaps you will repeat the second petition, “Thy Kingdom Come,” and then say something like: “Dear Lord, God and Father, ...Defend us against those who will not turn away their might and power from the destruction of your Kingdom so that they will be cast down from their thrones and humbled and so cease from their efforts. Amen....” [Perhaps you will do the same with the rest of the petitions, repeating each aloud, then saying a little prayer based upon your own need and God’s petition.]
Finally note this: you must always speak the “Amen” firmly, never doubting that God in His mercy will surely hear you and say “Yes” to your prayers. Never think that you are kneeling or standing alone. Remember that the whole of Christendom, all devout Christians, are standing there beside you and you are standing among them in a common, united petition which God cannot ignore. Do not leave your prayer without having said or thought, “Very well then, God has heard my prayer; this I know is sure and certain.” This is the meaning of the word “Amen.”
This in short is the way I use the Lord’s Prayer when I pray it. To this day I suckle at the Lord’s Prayer like a child, and as an old man eat and drink from it and never get my fill. It is the very best prayer (even better than the Psalms, which are so dear to me). It is surely evident that a real master composed and taught it...
[Luther goes on to suggest that he sometimes takes up the Commandments and/or the Creed in a similar fashion, if he has “the time and the strength before he prays the Lord’s Prayer.”]
Adapted from the American Edition of Luther’s Works, 43:193 ff.