A writer's workspace is all in the mind

There's writing and then . . . there's 'writing it down'. So much of our work is more than the actual crafting of words. Plot ideas, character development, research -- it doesn't all need to take place in front of a computer. A writer's true workspace is all in the mind. I proved this to myself yesterday at the dentist office.

There I was, pinned to a dentist's chair. I knew if I didn't find something to focus on, my brain would flip through a thousand frivolous ideas worth about as much as used dental floss and I hate wasting a good hour like that.

So I thought about my new MC, a young woman in her early twenties. I needed to know what events in her childhood were significant, what she is passionate about, what are her inner conflicts? While the dental hygenist did her work, I was happily engaged character development and my MC revealed a lot of new details about her life.

The longer I write, the more amazed at how portable my workspace has become.

What about you? Do you need to write in a specific environment? Or can you write 'on the fly'?  Do you have any odd places or moments where you've worked on some aspect of your writing?