From chapter two of John Owen’s classic Overcoming Sin and Temptation:
“The choicest believers, who are assuredly freed from the condemning power of sin, ought yet to make it their business all their days to mortify [“kill” or “put to death”] the indwelling power of sin.”
In other words, Christians battle sin and put it to death. They battle sin every day until the day they die. They never stop. They never let up.
And so Owen asks you:
“Do you mortify?
Do you make it your daily work?
Be always at it while you live.
Cease not a day from this work.
Be killing sin or it will be killing you.”