Psalm 1 speaks of the blessings of meditating on God's Word. But before we examine the blessings, we first have to consider why someone would meditate on something. And why would someone choose to meditate on God's Word—especially all the time as verse 2 indicates? I think there are three reasons. Maybe you can think of other reasons; if so, write them in the comments.
Psalm 1:2 gives us one reason as to why we would meditate on God's Word day and night: because we delight in it. When we delight in something, it occupies our thoughts; it is a joy to think on the things we delight in. Another reason we meditate on something is because we want to get out of it all that we can and all that is possible. A third reason would be to let the ideas and thought processes become our own, to incorporate them into the way we think and respond. In other words, we meditate in order to be transformed.
When we choose to meditate on God's Word for the purpose of transformation, we are declaring our faith in its ability to change us. With the harnessing of our thought life and with our time-expenditure choices, we are acting upon our belief that what God tells us about His Word is true: that it is living and active and sharper than a double-edged sword, having the power to divide and discern between soul and spirit.
It is precisely this ability to change us from the inside out that opens the door to the promises linked to meditation on the Bible. Notice that the promises aren't linked to meditation itself, but to meditation on the Word of God. It is the Word of God that contains the latent power of transformation. The promises of Psalm 1:3 reveal the power of God's Word.
There are four promises linked to meditation on the Word of God:
1. The one who meditates on God's Word will be like a tree planted by rivers of water. This promise indicates that we will have available to us all the resources we need to grow spiritually, to stay alive and healthy in our inner person.
2. The one who meditates on God's Word will bring forth fruit in its season. This promise shows purpose and productivity and significance. It also shows that we will have nourishment to give to others; our lives will bless others.
3. The one who meditates on God's Word will not wither. We won't become irrelevant or become dry with nothing to offer. We won't fade but will go "from glory to glory" (II Corinthians 3:18). The living waters of God's grace will continually be replenished in our lives and keep us fresh and green and flourishing—even in old age (John 1:16, John 4:14, John 7:38, Psalm 92:14).
4. The one who meditates on God's Word will prosper in whatever he does. That's an astounding promise! Meditate on that for a while!
When I read the final promise in verse 3, I can't help but think of the story of King Midas: everything he touched turned to gold. Now, granted, in the story King Midas' desire for gold was borne out of greed and very wrong priorities. But this promise from God is quite different. The obvious top-priority goals of the person who meditates on God's Word day and night is to know God and to live in a way that is pleasing to Him. When we do meditate on His Word for those reasons, God makes the most astounding promises, ending with "everything he does shall prosper"—the King Midas touch. Who wouldn't want everything they do to prosper?!
Joshua 1:8 echoes that same promise: "you will make your way prosperous and then you will have good success." In this verse we can observe the overarching reason for meditating of the Word of God: in order to observe or obey it. That's where the transformation lies, and that's what gives birth to these amazing promises. I am reminded of Jesus' question to Martha, "Do you believe this?" These promises—Do you believe them? They are yours for the taking. Delight, meditate, obey.