This verse could easily have found itself amidst the general blahs of Ecclesiastes. The comment is on the general futility of trying to do anything good unless God is in the work. The major difference between this and Ecclesiastes is that this really does drive home the point that God makes all the difference.
There’s not much deeper one can get than that. I would love to write a lengthy entry and have some deep thoughts to put down, but the truth is that this verse reminded me that all my efforts, no matter how well intended, will mean nothing if God is not involved. No matter how hard I strive to be a good husband, my efforts will fall flat if I have not invited God to be in the midst of my efforts and my marriage. No matter how good a father I try to be, I will always fall short unless God is in the middle of things. God’s presence matters more than words can say. Since I will fall short, His presence supplies what is lacking. As Paul wrote, God will supply all my need according to His riches in glory in Christ Jesus (Philippians 4:19) — and I need God to supply what lacks in every good thing I try to do.
Father, be invited into my life today. Not as an observer, but as a participant. Please show me the good You would have me do and supply what lacks in my feeble efforts. In You, I will do valiantly. Without You. I might as well throw in the towel. Unless You’re involved, my attempts at good things are in vain.