A couple of things have already gone wrong in my planning for the trip and now I can feel depression lurking just out of my sight (it's a shadow just out of my field of vision and a weight that can't quite be felt). This is what worries me; not that I might end up freezing to death on a Scottish hillside - that's okay, I can cope with that - but that when I get there, I find that I would have been better off staying at home. Now that's scary.
Update: having fixed a problem, I'm now feeling better. Turns out it was just common or garden disappointment.