Since this thread went dormant (take a trip through the way-back machine, Peli?), I've started taking piano lessons for the first time since I was 16. I found this GREAT jazz piano teacher who's totally breaking my habits down and rebuilding them again. Every single lesson, I leave with my head spinning about some new way to look at chord voicing or scale selection or SOMETHING. The main effect it's having on my playing right now is, it's turned even the tunes I'm fluid at into halting, jerky messes.
The main thing that keeps me motivated is the challenge of it. He's got me thinking in ways I've NEVER thought about music--and it's not easy, and it takes work, and I'm totally up for it.