[quote=Ergo]
I've both felt and seen what you are describing. I dare not speculate as to what the causes to this phenomenon might be, but I suppose it bears a resemblance to how people delight in the idea of going to the gym but despise the activity itself.
[/quote]
Heh, that sounds about right.

As for me, I have a very similar problem but it relates more to comics and stories, though occasionally it does affect roleplay characters. I make up characters to use in something, and I have all kinds of awesome ideas of things to do with them, but then I never really feel motivated to actually do something with them. I'm fine with just the drawing and random ideas of crazy stuff that they do or happens to them. I can't explain why this happens, it just does. *shrugs*