Happiness is an odd thing, it's a byproduct of something else. In other words, if you chase happiness you'll never find it. On the other hand, a person chasing Jesus receives incomprehensible joy! That isn't to say we don't have tough times, bad moods, days when we're down, but it does mean that even through those times we have joy in Christ.
It might surprise you to know when Paul wrote the book of Philippians, a book of Christian joy, he was actually in jail. Even though he was in the midst of hardship, he was able to literally write the book on joy. That't the joy of Christ!
5-disc set of teachings in the book of Philippians
278 minutes of audio
Compact Audio Disc