Don't pull your shoulders back, externally rotate them. If you pull your shoulders back, you will produce hyperextension in your lumbar region.
Check out Kelly Starrett and his excellent recovery book Deskbound. There is probably a lot going on with you (if you are a normal person) that is contributing to bad posture.
I'm not expert on this, and don't have standing desk (I mainly work outside anyway). But I did recently get Kelly Starrett's new book, Deskbound.
https://www.amazon.com/dp/1628600586/
EVERYTHING you want to know on this subject. He got the elementary school where his kids go to switch to standing desks - the first school to do this.
I was just saying that the article you linked had the reason that sit-stand desks were not working for people was because they would sit down most of the time...
I think the question should be is are their health benefits for standing with proper posture all day better than sitting? and I'm sure someone like Kelly Starrett would be able to give you a million reasons and a whole book on why standing is better than sitting.
I work in a call centre and one of my coworkers would just walk around the office after every other call. I personally will just try to get up a couple times between my breaks and walk around, I have access to a stand up desk but i find the position of the desk messes with my shoulder.
I've been tempted to invest in Kelly Starretts newest book standing up to a sitting world but I'm just too cheap and kinda too dumb to read that much.
For better health.
https://www.amazon.com/Deskbound-Standing-Up-Sitting-World/dp/1628600586
Same for me. I have a standing desk with a good barstool and a mini stair stepper that I hope will help.
This may help you: https://www.amazon.com/dp/1628600586/
You might be interested in Kelly Starrett's newest book, Deskbound, which is all about why sitting is bad and how to convert to standing desks.
I have the exact same issues. I got this book and it has helped a ton. https://www.amazon.ca/Deskbound-Standing-Up-Sitting-World/dp/1628600586
I am 36. This book rocked my world (and not just the sitting aspect), it might changes yours too for the better!
Hard Cover on this one could last a lifetime with proper care:
https://www.amazon.com/Deskbound-Standing-Up-Sitting-World/dp/1628600586