Here is a good description of sanctification making clear that we work but we do so by grace and not to earn or maintain our salvation.

“As Americans, we live in a culture that looks for fast, simple solutions to all problems…. we must testify that no such solution exists for the process of sanctification. Rather, we must adorn our faith with serious discipline and continuous work to grow in grace. But that seriousness must not be grim. We pursue holiness not to earn our standing with God, but because we are filled with love and gratitude to God for the standing that is ours in Christ. We pursue holiness sustained at every point with the grace and support that our God gives us in his church and among his people. We pursue holiness with the confidence that on the day that we are with Christ forever, we will be perfectly holy.”
– (Robert Godfrey, An Unexpected Journey, p. 127)