I tend to lose perspective.
I know, on a "brain-deep" level, that I am to do everything without complaining or arguing, as unto the Lord. I know that I serve an all-good, all-sovereign, omnipotent God, who is actively working His will -- the best of all possible designs for history. And I know that His will involves refining me to make me better suited to honor Him for Hist abounding grace.
But I often focus in on the small, temporal issues - "momentary light afflictions," as James calls them - and I complain. A lot.
"But God," I grumble, "it's hot and I'm exhausted but we keep losing," missing the fact that the Creator of everything set aside a Sabbath day for rest and for enjoyment of sports with friends. I feel childish typing it out now.
"But God," I complain, "there are these finals and I might not make a perfect grade," neglecting the provision of God to allow me to take college courses at all -- let alone my total dependence on His strength for any measure success in any aspect of life.
In my discontent, I declare the gifts and grace of the perfectly-gracious God to be insufficient by my standards. I place myself in judgment of the Most High Judge, and regard the Worthy One to be unworthy of my thanks.
I forget that I am a sinner, deserving only of eternal condemnation -- and so disdain the Christ who bore that condemnation for me in a measure of mercy unfathomable, choosing instead to add to the account of my sin by my unbelief.
And of all the "but God" objections I raise, I miss the "but God" of Scripture:
But God shows His love for us in that while we were still sinners, Christ died for us.[Romans 5:8][1]
God, forgive me where I have spited You, and show me daily Your majesty, that I might not forget it and may never cease to praise you.
[1]: http://esvbible.org/Romans 5:8