The above is what works for me and I love to get feed back from other developers on what works for you and how you make your self a productive developer.
I'm really interested about this 'flow' state you mention. I have found that I can get lost coding for hours but only if the problem / project is interesting enough. When doing something really really boring for a client or someone else, and without the tools and languages of my preference, I'm perhaps as 10% as productive as opposed in the environment of my preference.
The thing is, you can't always choose the projects you work on, and you can't always choose the tools you'd like to work with. Do you have any advice for improving productivity when you have these things against?
Have you read any of the writings by Tony Robbins ? he talks about this pain / pleasure principle and how you can like some thing you hate right now.