I guess I realised I was answering a slightly different question. I just felt it needed saying. People beat themselves up over not flying, when the fact that they didn't feel like challenging themselves is, as you say, a perfectly good reason for not flying. I think it's something we sometimes forget in the "must push yourself" culture of the keen GA pilot.
I couldn't agree more, Whirly. I use an aeroplane for getting myself about Europe quite a lot, and one of the satisfactions of doing that is demonstrating that it's as or more efficient than flying scheduled. But one of the most important realisations for me was that actually, when the effort and stress of planning a difficult trip with challenging weather start to cross the line between pleasure and pain, it's not defeat to sit in the back of a kerosene-burner once in a while.