God calls each of us to a particular vocation in life. The Catholic Church defines both particular vocations as three states of life: single, married, religious, and also a general vocation of all baptized believers.
A person can have many different callings in life. For instance a person can have a calling to marriage, to fatherhood, and to a certain occupation. In the Catholic worldview everything we do should be ordered toward discerning and responding to the will of God, the ultimate good in an imperfect world. Ordering our lives toward God’s desire is the way in which we get to heaven.
A vocation of marriage is God’s call for us to make a union with a person of the opposite sex to help each other grow in holiness and love for God and to be able to share in God’s creative work (bear children) if physically able. By becoming mothers and fathers God entrusts us to raise children by modeling the love of God for us to our children.
Vocations to the single life are a blessing from God. They allow someone to have more time to spend working on God’s plan. In marriage, spouses need to spend time on pleasing each other sometimes taking away time that might be spent on pleasing God. Single people need only worry about pleasing God.
Religious life, a call to ordained priesthood or a religious community, is a calling to serve God and his people in a unique way through prayer and service.
In any of these states of life God calls us to build up society in a manner that reflects the love of God. This is our general vocation as Christians. Even through work God wants us to build his kingdom. God calls us to meaningful work that brings value to humanity; work that does not exploit people for personal gain. In your occupation, ask yourself each day how your work will bring glory to God and help people rather than take advantage of others for personal profit.
Each vocation requires some sacrifice to die to self in the service of others. Perhaps this is the true meaning of vocation. Through serving others we act as God to others and we become more and more like Christ each day. While we might sin and fall short of what God desires for us, God still calls us to faithfully live our vocations in the hope that we will be with God in heaven some day.