I'm almost done with Ortlund's latest book, "Deeper." The Luther quote below is from that book. Here's a section from that book on mortifying sin: https://www.crossway.org/articles/you-need-christ-to-put-your-sin-to-death/
You Need Christ to Put Your Sin to Death
Christian salvation is fundamentally a matter of grace, rescue, help, deliverance—it is God invading our miserable little lives and triumphing gloriously and persistently over all the sin and self he finds.