This beautiful prayer is attributed to St. Patrick.  I like to pray this excerpt at the end of the rosary after the Hail Holy Queen:

 

Christ with me, Christ before me, Christ behind me,

Christ in me, Christ beneath me, Christ above me,

Christ on my right, Christ on my left,

Christ when I lie down, Christ when I sit down,

Christ in the heart of every man who thinks of me,

Christ in the mouth of every man who speaks of me,

Christ in the eye that sees me,

Christ in the ear that hears me.