29 Since the laity share in their own way in the mission of the Church, their apostolic formation is specially characterized by the distinctively secular and particular quality of the lay state and by its own form of the spiritual life. The formation for the apostolate presupposes a certain human and well-rounded formation adapted to the natural abilities and conditions of each lay person. Well-informed about the modern world, the lay person should be a member of his own community and adjusted to its culture. However, the lay person should learn especially how to perform the mission of Christ and the Church by basing his life on belief in the divine mystery of creation and redemption and by being sensitive to the movement of the Holy Spirit who gives life to the people of God and who urges all to love God the Father as well as the world and men in Him. This formation should be deemed the basis and condition for every successful apostolate. In addition to spiritual formation, a solid doctrinal instruction in theology, ethics, and philosophy adjusted to differences of age, status, and natural talents, is required. The importance of general culture along with practical and technical formation should also be kept in mind. To cultivate good human relations, truly human values must be fostered, especially the art of living fraternally and cooperating with others and of striking up friendly conversation with them. Since formation for the apostolate cannot consist in merely theoretical instruction, from the beginning of their formation the laity should gradually and prudently learn how to view, judge and do all things in the light of faith as well as to develop and improve themselves along with others through doing, thereby entering into active service to the Church. This formation, always in need of improvement because of the increasing maturity of the human person and the proliferation of problems, requires an ever deeper knowledge and planned activity. In the fulfillment of all the demands of formation, the unity and integrity of the human person must be kept in mind at all times so that his harmony and balance may be safeguarded and enhanced. In this way the lay person engages himself wholly and actively in the reality of the temporal order and effectively assumes his role in conducting the affairs of this order. At the same time, as a living member and witness of the Church, he renders the Church present and active in the midst of temporal affairs.
Source: Apostolicam Actuositatem (Vatican.va)