I don't drive car much and when I do it's interesting enough to be able to focus.
But I am unable to watch movies without company because I will immediately switch tasks, either physically on my PC or mentally, focusing on something else. And I annoy everybody who I watch movies with by commenting things we see because this switch helps to flush temporary boredom.
The list of symptoms you read, did it include hating yourself and thinking yourself a loser because you failed to complete (or even start) important tasks, lost jobs, failed in school, even when you knew how important it was to pay attention, stay on task, and get shit done?
So how do you work like that? I'm having real trouble working, since my brain just jumps from one idea to another and I have to always keep the task at hand in my mind, which is pretty damn hard...
I usually have a zillion of small tasks and I switch between them real fast, and at the end of day most of those are done.
Version control systems and command line histories help greatly.
When I need to write a sizable chunk of code: I might spend a hour or two surfing the web, but when I finally push myself in I get into the zone that Joel described without much problems.
Bonus points: Being ADHD, I'm able to switch tasks and spend a few minutes doing another task without leaving the zone! Resuming without productivity loss. And I absolutely neverming talking, I can talk and be in the zone at the same time.
But I am unable to watch movies without company because I will immediately switch tasks, either physically on my PC or mentally, focusing on something else. And I annoy everybody who I watch movies with by commenting things we see because this switch helps to flush temporary boredom.