When people do not know God, they live to please themselves. Happiness is a central motivation for the unsaved, but happiness is inherently subjective.
God’s purpose for us is our sanctification. To be sanctified is to be separate from the world. We will never be completely made into the likeness of Jesus while we live, but as this process continues, we learn to put the things of this world into the right perspective and we learn that God provides everything we need. Therefore, we can be joyful.