The Bible has quite a number of references to trees and fruit. In Galatians 5:22-23, Paul says that the fruit of the Spirit is nine fold.  Love, joy, peace, long-sufferering, gentleness, goodness, faith, meekness and temperance.

But fruit doesn't just happen.  It grows on a tree.  And Psalms 1:3 explains it. There is a tree next to water.  The tree draws strength from the water--which represents God, or Christ.  The trunk of the tree is the Holy Spirit which spreads God's words to us--the limbs.  If the tree is planted the water, the limbs--you and me--produce fruit.  Christians don't have to grunt and groan to produce fruit, it is the automatic result of where the tree is planted.  Where you are planted.  

God is the source of the message.  The tree is the source of our inspiration.  You...the limb, "shall be like a tree planted by the rivers of water that brings fruit in...season.  his leaf also shall not wither..."  You may have a season when your leaves are withered and you feel helpless, but don't despair,  Spring is coming.