Try something totally different. It could be a totally different technology: say Ruby on Rails or maybe Flex/Flash & Actionscript. How about becoming a designer? Something you have never considered before or never thought of as worthwhile. Something that brings back the "lightness" feeling you seem to be missing.
I think change is certainly key as the catalyst for a turn around your state of mind.
That said, from my experience, I wouldn't expect to ever have an immediate, deep psychological turn around in response to any particular change, even a radical one - it always takes time. But change is key.
Some common wisdom: It's easy to be scared of change - often easier to deal with a bad situation - not even really realize it's that bad - than face the unknown. But the unknown is almost always not as bad as you think.
I like the idea of seeking "lightness". Heaviness is exactly what burn out feels like, as if everything is 100 times more painful than it really is/should be/once was.
