I've been standing at my desk at work for a little over three weeks. The first week was really difficult. My muscles were not used to being used all day and they did not like it very much. I did have a little bit of knee pain at first and really thought about switching my desk back to "normal." I'm glad I didn't.
Even if my body didn't want to adjust instantly, it seems to have come around. I'm not sure if I've improved my posture, or even my muscle strength, but I feel better for making the change. I do know that I am falling asleep really quickly every night, but that may be pure coincidence.
One of my worries was how coworkers would react. That couldn't have been more misplaced. I found out that there is another person in the office who already has a standing desk. I have never seen in her office, so I didn't realize it. Many people have asked to see HOW I set it up, with only a few people asking me why. I've received thumbs up from the IT guy. Maybe the message about the ills of sitting all day have really reached people.