I recently read a nice post from a Microsoft employee that brought back some not-so-distant memories
http://makingtheswitch.wordpress.com/2007/04/28/when-did-i-become-such-a-tool/
I'm sure a lot of other developers have been through the same experiences and are searching for (or have found) their healthy zone - where work is play, and development is exciting and fufilling.
Every day is a challenge to yourself to learn new things, explore, research, and share.