Most of Christianity that I've come into contact with has a well developed theology of work; sometimes called the Protestant Work Ethic, it is summarized in the verse, "Whatever you do, do it heartily, as if unto the Lord." (Col. 3:23). A mature Christian is characterized by hard work, and I do not wish to detract from that, but there is a counterpart to theology of work: theology of play.
It would probably be easier to defend a point of doctrine involving great self sacrifice - that a Christian should be so loyal to Christ that the prospect of being tortured and killed for this devotion is regarded as an honor, that a Christian should be willing to serve in boring and humiliating ways, that a Christian should resist temptation that takes the form of an apparent opportunity for great pleasure - but I will still state and explain this point: a Christian should be joyful, and furthermore that this joy should express itself in play and celebration.
When Paul describes the fruit of the Spirit, the first word he uses is love. Love will certainly apply itself by hard work. He goes on to describe it as patience, faithfulness, self-control. Patience, faithfulness, and self-control all have important application to hard work. But the second word is joy. If the fruit of the Spirit will yield hard work, it will also yield expressions of joy.
C.S. Lewis said that the greatest thing that the Psalms did for him was express the joy that made David dance. Doctrinal development is one of the reasons that God gave us the Bible, but it is not the sole reason. I would not by any means suggest that omitting Paul's epistles would improve the Bible, but there is a lot of the Bible that I read for the sheer joy and beauty as much as anything else. Psalm 148, one of my favorite, beautifully embellishes the word, "Halleluyah!"