Ask HN: Do you work at a standing desk 7+ hours a day?

Motivated by a recent thread (http://news.ycombinator.com/item?id=1834671), I thought I would reconsider my choice to "slowly kill myself" by sitting at a desk all day. I can't avoid being at a desk all day, but I can avoid sitting at one. Thinking about standing for 7 or 8 hours a day, however, makes me recall the long hours I spent as a teenager standing in a burger line at a fast food restaurant; and I cringe. Standing for long periods is tough, and I'm wondering how many software developers or other people who work at computers all day have tried or are currently using a standing desk and what your thoughts are?