Do you remember your Baptism? If you were baptised as a baby, quite likely not. I was 16, so I do. I chose to be baptised as a sign that I follow Christ.
Baptism has always marked someone joining the Church, a sign of faith, a sign of dying with Christ (going down into the water), a sign of being raised with Him (coming up out of the water); it is a sign that I choose to live ‘in Christ’, that my sins were dealt with by His death, that my old life is gone, and that I have new life in Christ as I dedicate myself to living Christ’s way.
I made that choice, and I still choose it.
If your parents made the choice for you, that isn’t a problem. But you must still choose for yourself. In Confirmation you acknowledge the baptismal vows made by your parents and godparents, and you confirm them and take them on for yourself.
We do all this because Jesus is the Way the Truth and the Life (John 14:6), and we choose to live following His way – and if that means changing how we live (which it does), we do that willingly – because Jesus Christ is alive and “is my Lord and my God” (Rom 10:9; John 20:28)