The psalmist declares a holy revulsion that must dwell in your heart against anything that challenges the law of God. If you consistently struggle to conquer an area of sin in your life, it may be that you do not hate that sin.
One sin God hates is divorce (Malachi 2:16), not because He wants to be legalistic but because He knows the terrible consequences you will suffer from it. Satan's deception concerning this sin and all sin is so devious and the consequences of disobedience so eternal that you must develop a passion against all sin, for it destroys people's souls.
Double-minded or undecided people (Psalm 119:113) are those who mix God's law with their own reasoning, listening to the voice of personal opinion rather than the voice of truth. Such compromisers lead the godly astray and are unstable in all their ways (James 1:8). If you are double-minded, rid yourself of lukewarmness, and purify your heart.
If you don't hate sin, you will fall into it. Love God and hate sin, and you will always walk in the path of righteousness.