The psalm indicates a consciousness of sin and a desire to avoid it. It is not a confessional psalm. Awareness of Sin. Our inclination is to blame others, minimise sin. The Psalm is full of determination to choose to do what is right.
Sin is a choice.
You don't have to sin. It is a deliberate act of the will to what is known to be against God's wishes. It is not just a cold, intellectual act of the mind to do what is right and guard from sin. There is an emotional response to sin. There is indignation, hate, loathing and tears at the sight of sin.