Much of the misery of this struggle with sin is due to the conscience continually condemning the believer for giving way to sin. But the great and glorious fact of the gospel of God's grace is that though our conscience condemns sin, God never condemns us (speaking only to born again believers here), because He sees us in Christ, who has already paid our penalty for sin on the cross. So we are free and beyond condemnation and judgment: "There is therefore now no condemnation to those who are in Christ Jesus" (Rom. 8:1).
The life we now have flows down from Him, its fountain and source, into our souls. "Because I live, you will live also" (John 14:19), are His own words to us. Our response is: "Christ - is our life" (Col. 3:4). This is the great soul-delivering truth of God. He does not see us in our old nature any more. He is done with that and sees us only in the new life we have in Christ. And He has given us His Spirit to dwell in us, to develop His new life in us and to give us His power over sin.
So Christ is the answer to all of our struggles. We must stop trying to overcome the sinful tendencies of our old nature in our own strength and begin to let Him work in us that deliverance and victory over sin we so much long for. Likewise, we have no power to produce fruit, even though in our new nature we long to do so. What relief from our misery when we come to the end of ourselves and begin to trust Him. When we realize our powerlessness and look to the Lord, He gives victory over sin and produces fruit that brings joy and peace.
Christ gave us a simple illustration of how this works: "As the branch cannot bear fruit of itself, unless it abides in the vine, neither can you, unless you abide in Me. I am the vine, you are the branches. He who abides in Me, and I in him, bears much fruit; for without Me you can do nothing" (John 15:4-5). Where did the branch get the power to produce such wonderful fruit? Not from itself, but from the vine which sends its invigorating sap flowing into the branch to produce fruit.
Never lose sight of the great fact that Christ is the answer for every trouble. Without Him we cannot overcome. The more we keep in touch with Him the more fruit we will produce. Without Him fruit bearing is impossible. Without Him we will never have true and lasting happiness. He is the source of all joy. In Him we can have a happy life!
"These things I have spoken to you,
that in Me you may have peace.
In the world you will have tribulation;
but be of good cheer,
I have overcome the world."
EC Hadley borrowed from Stem Publishing
ps...to 'be happy" is not the goal of life, though many pursue that with great zeal. The goal of life is Christ....joy is the result of salvation in Christ and understanding the truth.