All growth in the Christian life is a work of the Spirit, by the grace available to us because of Jesus.
"Dear friends, you always followed my instructions when I was with you. And now that I am away, it is even more important. Work hard to show the results of your salvation, obeying God with deep reverence and fear. For God is working in you, giving you the desire and the power to do what pleases him." – Philippians 2:12-13
These verses show the relationship between our efforts and the work of the Spirit. Although we must make choices to grow in godliness and avoid sin, even those choices are a gift from God by the Spirit working in us to change our desires and give us the power to grow in obedience.