When you sin one day, you forget about it, and the next day, you sin again—The second sin hardly weighs on your conscience because you have already forgotten the first.
Know your sin well. See it for what it truly is. Know its frequency and what tempts you into it. You will never come to hate your sin until you learn the extent of it. You will never learn the extent of it if you do not keep a fervent watch over your own soul.
See all of this in light of how good and gracious God has been to you. Only when you see your wickedness as it truly is in light of the righteousness of God will you come to hate it as you should. God hates sin because He is holy—it is because God is holy that you must hate sin as well.