"You don't need to use many or high-sounding words. Just repeat often, 'Lord, show me your mercy as you know best.' Or, 'God, come to my assistance.'" St. Marcarius of Alexandria

It is not many words that God wants to hear. He wants us, for our sake, to turn our hearts to him. Just call on his name with the sincerity of our hearts, not to impress him, but to love him.  This is what St. Paul meant when he said that we should pray unceasingly. The Desert Fathers used to say short prayers like: "Jesus, Son of God, have mercy on me a sinner." They would do this throughout the day to keep their minds and hearts centered in God as they went about their daily activities. When our life is so focused, our hearts will be in the presence of the Lord continually.