What does Psalm 1:3 mean?

Every fruit grower knows it would be unwise to plant a fruit tree in the middle of a desert, far from a water source. The tree's leaves would wither, and the tree would never yield any fruit. For fruit trees to grow healthy and bear fruit, they must enjoy an abundant supply of water.

The blessed person—one who follows and considers the words of God (Psalm 1:1–2)— is like a tree planted by streams of water. They are spiritually healthy, vibrant, productive, and successful because they take advantage of an abundant supply of the water of God's Word. In such a person's life, the inspired Word becomes the illustrated Word—he or she obeys and lives out the truths of God's Word. Blessed people bear the fruit of the Spirit: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control (Galatians 5:22–23).

It should be noted that fruit does not grow as soon as a tree is planted, but the fruit will appear in season. The spiritually productive life is one of growth, and in due season the consistent watering with God's Word will bear fruit. The main application here is spiritual—while earthly success is more likely when we follow truth, material prosperity is not guaranteed for all believers at all times.