Fight sin at its earliest stage — Jesus teaches in the Sermon on the Mount that the beginning state of sin (lust, anger) is already where you've lost the fight. Draw personal boundaries far from the sin, not close.

Matthew 5: looking with lust = adultery in the heart. The fire analogy: put out a fire when it's small, not after 20 minutes. Draw boundaries early. Don't fight the battle at the point of full temptation — fight it at the first flicker.