When Christ was on the cross, He struggled against Sin. He was not struggling not to sin, but struggling against the thing Itself. Can we all agree that the moment Christ died was the moment at which this struggle ceased?
"In that He died, He died to Sin once for all time, yet in that He is living, He is living to God. Thus you also be reckoning yourselves to be dead, indeed, to Sin" (Romans 6:10-11).
At Christ's death, it was no longer possible for Him to be vexed by or wrestle against Sin. By reckoning that
death to ourselves, NOW, we can live lives free of the vexations and struggles against Sin. This does not mean that we no longer sin, but that we are no longer vexed by or struggling against it. Being free of the struggle, what now is to be our occupation? We are free now to live to God.