I recently finished reading Surprised by Joy by C.S. Lewis.
Lewis is a wonderful Christian author who is perhaps best known for his Narnia series of books. He's also written some wonderful Christian books such as Mere Christianity and The Screwtape Letters. Surprised By Joy is mostly an autobiography of his young life but focuses more on his adoption of Christianity towards the end. Lewis was fascinated by the concept of joy. The book comes to the conclusion that you can't seek out or make joy happen because when you try to focus on joy itself you stop focusing on what causes joy, thereby causing your feelings of joy to diminish. In other words, joy is a byproduct of the experience of contemplation. Joy is a longing for that which the world can't contain, joy is a signpost pointing to God.
This is a wonderful book well worth reading.
The book was apparently made into a film called Shadowlands which I have yet to see.