Do you ever have trouble concentrating?
Apparently, one of Brother Lawrence's correspondents had written to him confessing that his mind would wander during times of prayer. The first sentence of BL's reply is, in itself, an empathetic encouragement: "You tell me nothing new: you are not the only one that is troubled with wandering thoughts. Our mind is extremely roving."
BL quickly goes from commiseration to wise words of advice:
I believe one remedy for this is to confess our faults, and to humble ourselves before God. I do not advise you to use multiplicity of words in prayer; many words and long discourses being often the occasions of wandering; 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 recollect it; the will must bring it back in tranquility; if you persevere in this manner God will have pity on you.
Truth is...it does no good to wallow around in our shortcomings. Pick yourself up, brush yourself off, and start all over again.