Vices develop slowly and subtly. It starts with nightly drinking, and it ends with alcoholism; it starts with regular porn consumption, and it ends with sexual dysfunction and addiction; it starts with one lie, and it ends with a whole story fabricated. Sin has a way of pulling a person in, so that before long there is no easy way.
Likewise, vices develop in a subtle way, so that we don't think there is any trouble or problem when there is. Of course you're not an alcoholic—yet; but you seem to put few if any limits on your drinking, and if you keep it up, alcoholism is not far off. And sure, you're not porn-addicted—yet; but engaging in that kind of intensely pleasurable behavior is not the kind of thing given up easily. And the more you do it, the more you are desensitized to the experience, and the more intense it must be to be as pleasurable as the time before. This is the recipe for addiction.
I've used alcohol and pornography as easy examples of addictive behavior. But what is terrible is that most sins cement themselves in our character so subtly that we are less likely to discern that there's anything wrong. You don't forgive one person, you criticize another, you judge people as you pass them by during the day, you joke a bit aggressively with your friends, you get visibly frustrated with the shortcomings and weaknesses of others. Now you're a jerk and you're convinced everyone else is in the wrong.
What's the solution? Paul says: put on Jesus Christ. You have to assume a new identity, change your way of thinking about yourself and others, follow a different example: that of Jesus Christ v