That is, "I've done what I was supposed to do."
This psalm follows the reminders with a plea for help, a plea that is based on the psalmist's innocence: Don't give me the punishment that sinners deserve, those who murder, scheme, or defraud. I don't deserve that punishment because I am blameless.
Most of us would have a pretty tough time praying those verses expressing innocence as honestly as Job could have. But, we can be just as sincere asking for protection and mercy.
The psalmist was pretty certain that God was going to make things right. The last verse is "My foot stands on level ground; in the great congregation I will bless the Lord."
Back to us: if we do get protected, if we do benefit from God's mercy, do we remember to give thanks?