"Thinking that our posture wins favor with God or that it ensures an answer to prayer reduces prayer to magic; however, if we refuse to place ourselves under some particular, reasonable physical discipline, our pride can separate us from God." Dr. Ellsworth Kalas, "Longing to Pray"
Prayer prompt (also from Dr. Kalas' text): "See for yourself how the mood changes as the posture changes. Sit and pray, and prayer takes on a conversational quality. Stand, and you feel you are making an appearance before the King. Lift your hands, and a special sense of adoration engulfs your prayer. Put your head down, and you feel awe, humility, perhaps even shame; lift your head, and there is a sense of glad openness."
Today try more than one of these postures in your prayer time that you usually don't use.