Keep your attention within yourself

You should observe three things before all else: freedom from all cares, not only about bad and vain but even about good things…your conscience should be clear so that it denounces you in nothing, and you should have a complete absence of passionate attachment so that your thought inclines to nothing worldly. Keep your attention within yourself—not in your head, but in your heart.

~ Symeon the New Theologian, Three Methods of Attention and Prayer