I've recently migrated to a standing desk after doing a nasty back injury about a month ago. I physically couldn't sit...or rather couldn't move to and from the sitting position.

However, I found fairly quickly that I needed to get a stool for occasional sitting. If you've been in a desk job for 15 years like me, going to a standing work position is killer. Worse for me was I found that I couldn't think standing up! I had to sit to think. I think it's important as a transition, otherwise you'll most likely go back to a sitting desk after 2 weeks.

A month or so later and I don't use the chair nearly as much, and I'm actually enjoying getting sore feet BEFORE my back hurts.