As the old PC still contains most of my old files, I've had to access it quite a bit. And in the process I fell in love with the setup so much that I actually make conscious effort to use it more. First, obviously I love the larger display. Second, it is refreshing having to switch from prolonged sitting position to standing position from time to time, with the standing desk being just 2 steps behind my real working desktop. By the way, this is my sitting desk in case you're curious. And you can rightfully imagine that it's normally a bit more messy than this. Ha!
I didn't realize there are health benefits for standing desks, and that employees at Google and Facebook had to be "promoted" to use one. I guess I should promote myself and use it a lot more regularly!
By the way, personally I feel it is in fact more tiring standing than walking/hiking. Heels and ankles really get stiff quickly and I'd need to alternate my standing leg and perhaps stand my my toes for a change. I wonder if there is a physiological reason for this.
UPDATE: My skepticism above was somewhat validated by Cornell University's take:
The use of a height adjustable worksurface for sitting and standing work is becoming fashionable. However, there is scant evidence that sit-stand furniture has cost effective benefits. The evidence suggests that there may be a reduction in back discomfort, but the research for this has not used adequate comparison groups (e.g. testing people who stand for the same time at the same frequency without doing keyboard/mouse work). There is no evidence that sit-stand improves wrist posture when keying or mousing. Logically, the real benefit of sit-stand is just that, changing between sitting and standing. But standing in a static posture is even more tiring than sitting in a static posture, so movement is important. We recommend that the most cost effective way to obtain the benefits from sitting and standing is for people to sit in a neutral work posture and then intermittently to stand and move around doing other things, like filing papers, making phone calls, getting coffee, making photocopies etc.) rather than trying to keyboard or use a mouse while standing.