In the Rite of Confirmation, the Bishop (or a Priest who represents the Bishop) extends his hands over you and asks the Holy Spirit to come to you with seven special graces, or gifts: wisdom, understanding, right judgment, courage, knowledge, reverence, and wonder & awe.
Confirmation is the sacrament whereby God completes the graces of a person’s baptism and deepens His seal within them, marking them as belonging to Him (2 Corinthians 1:22, Ephesians 1:13-14). When received within a life of faith, the outpouring of the Holy Spirit through confirmation empowers us to live the Christian life, which we simply couldn’t do otherwise. Thus, it is not a person’s “adult choice to be Catholic”, rather it is God who chooses us, and we can then choose Him day by day.