Primarily people are called into right relationship with Christ.  On a personal level the three pillars of spiritual life are called for; on a public level, we perform our duty (our "work") as a body of believers.  In the West, two forms of liturgy are available:  the first takes on a more reserved character in the Extraordinary Form and a freer character, circumscribed by limits, in the Ordinary Form.  The limits are there specifically in order to ensure that we do not begin worshiping ourselves, the personality of the priest, our cultures and customs, our own gifts, etc. rather than God.  Once we start changing liturgy to reflect our whims, we cease right worship of God and focus our attention elsewhere.