If you're having difficulty settling into prayer, you may want to try The Relaxation Response method developed by Harvard researcher Herbert Benson, MD.
Here's what you do: Choose a simple prayer or statement reflecting your spiritual roots. For example, you could use the word "shalom" or "om," or the phrase "The Lord is my shepherd" or "Hail Mary, full of grace." After you have chosen your phrase, close your eyes, relax your body and mind and engage in deep breathing, by inhaling through your nose and exhaling through your mouth. Say your word or phrase silently as you exhale. When stray thoughts come by, gently release them and continue your mantra. To achieve relaxation, use this technique for at least 10 to 15 minutes each day.