It is not so true that "prayer changes things" as that prayer changes me and I change things. God has so constituted things that prayer on the basis of Redemption alters the way in which a man looks at things. Prayer is not a question of altering things externally, but of working wonders in a man's disposition.
Get into the habit of dealing with God about everything. Unless in the first waking moment of the day you learn to fling the door wide back and let God in, you will work on a wrong level all day; but swing the door wide open and pray to your Father in secret, and every public thing will be stamped with the presence of God.