Health advice for us at desks

No special furniture required. Just sitting is bad, but so is just standing. Therefore:

Sit to do computer work. Sit using a height-adjustable, downward titling keyboard tray for the best work posture, then every 20 [or 30] minutes stand for 2 minutes AND MOVE... just walking around is sufficient.

So, maybe pace back and forth in the office and write on the whiteboard. The trick is the frequency. I don't want a beep every 30 minutes, but perhaps a discreet blinking light in the corner of the screen. I'll have to experiment with this.

My biggest concern is loss of "flow." You know the movie trope, a montage of a hacker typing for hours? I do more scribbling on paper and whiteboards (and forego a soundtrack), but it's basically the same thing. I really enjoy having a big block of time to work on Just One Thing. (The great danger is the temptation to "work" for a long time on reading my favorite economics blogs or perfecting a blog post of my own.)

Unfortunately, it is not clear to me how important "flows" of an hour or longer are to my productivity, nor even how I could perform a self-experiment to find out. (Is there applicable large-N psychology research?) My subjective experience, which I should not naively trust, is that some problems are intricate and that I need a big block of time just to get all the moving pieces properly configured in my working memory. On the other hand, many flows have turned out to be inefficient ex post because of a wrong turn made early in the flow. One the third hand, it is not clear that breaks help detect wrong turns sooner. For an extreme example, it seems easy to dabble briefly in something every day and not notice a lurking error for many, many days.