[DanielStraight]

I'm only one data point, but I felt significantly better in two or three days after hacking together a sit/stand desk. I can point to specific aches, pains and other minor medical issues that I simply no longer have now that I divide my time between sitting and standing.

[SomeCallMeTim]

I'm another data point. Built my own standing desk and bought a drafting chair; I frequently stand most of the day, and it's improved my posture markedly.

I'd gone through a series of various expensive "ergo" chairs, and yet I would get a feeling of suffocation when sitting for too long. Now I can work for extended periods without the need to "get up and walk around."

And when particularly good music comes on the radio, I can dance to it during compiles. Yes, I work in an office where no one can see me. ;)

[Isamu]

It took me more like a month to get used to it after I set up my standing desk.

I feel like my posture is better and my back is stronger.