Let the words of my mouth and the meditation of my heart be acceptable to you, O Lord, my rock and my redeemer.
In discussing this verse, Calvin talked about our need to be "governed by the Holy Spirit." And this, I believe, is what Jesus was talking about in the Sermon on the Mount, when he made the connections between thoughts, words, and actions.*
With the advent of social media, we can now see a need to include posts, tweets, and status updates in our prayers for acceptability. For example, while God's will might be for me to go to church on Easter, if I spend the trip there and back tweeting vitriol against my neighbors, I might have to admit to an acceptability problem. Though my outward acts are intended to appear to be pious in nature, I am clearly not "governed by the Holy Spirit" in the aspects of my life that really matter.
I'll close with Calvin's paraphrase of the first part of this little prayer:
I beseech thee, O God, not only to keep me from breaking forth into the external acts of transgression, but also to frame my tongue and my heart to the obedience of thy law. Amen.
*See Matt. 5:21-22, 27-28