Here is a great quote I found over at The Resurgence regarding prayer: "Müller excelled in prayer only after he meditated on Scripture, that "getting his soul happy” was accomplished through meditation, which enabled communion with God through prayer." Here is the story from an entry in George Müller's diary, dated May 7, 1841 that brought about this conclusion:
I saw more clearly than ever that the first great primary business to which I ought to attend every day was, to have my soul happy in the Lord . . . not how much I might serve the Lord, . . . but how I might get my soul into a happy state, and how my inner man might be nourished. For I might seek to set the truth before the unconverted, I might seek to benefit believers . . . and yet, not being happy in the Lord, and not being nourished and strengthened in my inner man day by day, all this might not be attended to in a right spirit. Before this time my practice had been . . . to give myself to prayer after having dressed myself in the morning. Now, I saw that the most important thing I had to do was to give myself to the reading of the Word of God, and to meditation on it, that thus my heart might be comforted, encouraged, warned, reproved, instructed; and that thus, by means of the Word of God, whilst meditating on it, my heart might be brought into experimental communion with the Lord.