This is the beginning of a new walk with the Lord. I love the analogy that Jesus uses in John 3 when he refers to baptism as being born again. We've heard "being born again" so often we forget how shocking maybe that term was to Nicodemus. But it's so true. You have a fresh start. You are born into the real humanity that God intended for you to be. The main point after the new birth is not that you keep yourself from returning to the old world.
The purpose after the new birth is to grow into the full measure of the true human, the man that represented what real humanity looked like, to grow into the image of Jesus Christ.