I can easily recognize the down periods, but like segmondy, I can't (or won't) do anything about them. In a free work environment, it's easy to rationalize not working right now with "I'm listless, it's better in the long run to rest." But too many of those occasions point to larges issues, such as not really caring about the work.
I self-identify with being intrinsically driven, as well as caring about my work. So now there's the meta-guilt of not being interested and motivated enough. Along with the normal guilt of "why won't you just harden the F up and do something."
Anyway, if you have written anything else along these lines, please post a link. I'd be very interested in reading it!