Martin Luther wrote the following to his barber when asked for advise on how he should pray.
So a good and attentive barber keeps his thoughts, attention, and eyes on the razor and hair and does not forget how far he has gotten with his shaving or cutting. If he wants to engage in too much conversation or let his mind wander or look somewhere else, he is likely to cut his customer’s mouth, nose, or even his throat. Thus if anything is to be done well, it requires the full attention of all one’s senses and members, as the proverb says, “The one who thinks of many things, thinks of nothing and does nothing right.” How much more does prayer call for concentration and singleness of heart if it is to be a good prayer!
