I've just gotten my hands on a book on Christian contentment I've been interested in and will probably be sharing a bit from it as I get around to reading it.
I just wanted to share a preliminary thought. God knew exactly the situation we would be in right now, however miserable it is (mine has been pretty awful the last few days). If it's in our control to change and improve our situation and it doesn't oppose the will of God, I certainly think it's wise to pursue change. That said, I also think we're called to be content with where we are because we know God has put us exactly there.
But the difference for the Christian is this. We may be called to be content, and we should be (see Paul... anywhere), but if God has called us to something specific and we're not somewhere in the journey on the way there then contentment should not be on our radar. In fact the belly of large fish might be more suitable. But that said, the road to Nineveh deserves as much of our contentment as when we arrive there.