1 Now it came to pass, as He was praying in a certain place, when He ceased, that one of His disciples said to Him, “Lord, teach us to pray, as John also taught his disciples.”
2 So He said to them, “When you pray, say:
Our Father in heaven,
Hallowed be Your name.
Your kingdom come.
Your will be done
On earth as it is in heaven.
3 Give us day by day our daily bread.
4 And forgive us our sins,
For we also forgive everyone who is indebted to us.
And do not lead us into temptation,
But deliver us from the evil one.”
It's been said that a man will suffer in this life if he doesn't pray, but I think they have this confused with the material and physical aspects of life. What will suffer is the life of Jesus in him, which is norished not by food, but by prayer.
It's not so much that "prayer changes things" as it is that prayer changes us. Our conversations with God bring us closer to Him and we find that His ways are so much better than anything we could choose for ourselves.