That question came up on another board a few days ago. Here's my thoughts on it...
The last time I was truly excited about a build was a certain 29 pickup (that you may vaguely remember) everything about that project seemed inspired, cool, easy, etc... Although I've built quite a few since then, they've all been "interesting" projects. My most recent project, a 32 Vicky, has that old feeling about it. I'm constantly thinking about the next part of the build, planning for the next step, daydreaming new ideas, picturing the finished model, etc...
Yeah, inspiration is the key! I realize most of my projects die because something didn't work out right, that color sucked, that ride height is wrong... Comes right down to it, they were only interesting, not inspired.
Thats my story and I'm sticking to it!