The Joy of Mantra
When inhalation occurs naturally, mentally speak a chosen word, such as "God," "peace," "joy," or any pleasant word. When exhalation occurs, again mentally speak the word. Feel that the sound of the chosen word is blossoming in your mind or your field of awareness. Do this without effort and without anxiety about results. When a state of conscious, calm awareness is experienced, discontinue listening to the word. Be still, letting that meditative calm persist for several minutes until you feel inclined to conclude the practice.
~Roy Eugene Davis
Using a mantra is an excellent way to calm the busy thoughts in your mind. You can also try the Sanskrit words "so-hum". This phrase means "I am that which I seek", yourself at your highest human potential. Say "so" on the in breath, and "hum" on the out breath. As your meditation session unfolds, you will find that you no longer have to make a conscious effort to repeat the words and that they come naturally with each breath. They will repeat themselves. When the mantra takes you from concentration onto the deep peacefulness of meditation, you can let go of the mantra.