I have a standing desk. I seriously need to force myself to use it, though. The last time it's been moved up is about a month ago.

my trick: start the day standing and try to stand for as long as i can. i usually stay standing til my lunchtime walk and when i get back from my walk i still have energy to stand. if i sit then my focus wanes.

When I first started with my standing desk, I found it particularly useful to combat lunch coma.