E are supposed to be co-laborers with God. Of course, for that to be the case, we have to get in on what He is already doing... because He certainly is not going to adjust His plans to fit our agenda nor forsake His own will in order to follow after our priorities or methodologies. There is definitely a great chasm of divergence between His works and ours. Most obviously, we are naturally unrighteous (Romans 3:10), whereas He is infinitely and always righteous in ever act and attitude (Psalm 92:15).
This song was written for the "Sabbath day" and is therefore a song of worship AND instruction. As such, the key point that stands out to me is the fact that God's work can make us glad (Psalm 92:4). On the contrary, we should all know that our works do not make us glad. Our works (in our energy) are perpetually dissatisfying and faulty.
But, when God steps in; when He gets involved; when I know without a doubt that it is Him working and not me working without Him... or against Him... or even for Him (but in my own strength), then and only then does the joy of the Lord suddenly show up. When will we ever learn that God is not interested in seeing what we can (or can't) do, He is interested in revealing to us what He can do? "It is good to give thanks unto the Lord" (Psalm 92:1). It is not good for us to try to persuade the Lord that He should be thankful that He has us on His side. Our victories are found only in Him (Psalm 92:4). His thoughts and program are deep and perfect... our thoughts and plans are shallow and flawed (Psalm 92:5). And only fools imagine otherwise (Psalm 92:6).