this calm and gentle prayer is from the classic english book the cloud of unknowing. set aside a time each day. as with all prayer, regularity is important. start with fifteen minutes, and expand that as you feel called.
choose a sacred word. it could be anything. some possibilities are Jesus, mercy, peace, still, Mary, amen.there are lots of centering prayer groups around, and more helps can be found at contemplative outreach.
introduce the sacred word gently. it is not necessary to repeat it insistently. when thoughts arise, of whatever sort, return gently to the sacred word. in the course of your prayer, the word may become vague or disappear from your mind. but when thoughts come, return gently back to the word.
at the end of the time, rest camly for a couple minutes, perhaps pray the Lord's prayer slowly, and then get up.
pages on christian prayer: