Keep in the presence of God…

One way to recall the mind easily in the time of prayer, and preserve it more in tranquility, is not to let it wander too far at other times. You should keep it strictly in the Presence of God; and, being accustomed to think of Him often, you will find it easy to keep your mind calm in the time of prayer, or at least to recall it from its wonderings.
–Brother Lawrence (1614-1691)

Hold yourself in prayer…

Hold yourself in prayer before God, like a dumb or paralytic beggar at a rich man’s gate. Let it be your business to keep your mind in the presence of the Lord. If it sometimes wander and withdraw itself from Him, do not much disquiet yourself for that: trouble and disquiet serve rather to distract the mind than to re-collect it: the will must bring it back in tranquility. If you persevere in this manner, God will have pity on you.
–Brother Lawrence (1614-1691)