So much this. Also give standing desks a try. That helped me to fix my posture a ton (not only while working on the computer, but while standing/walking/etc overall) and also made half of my lower pain back go away.
How long do you manage to work standing up? do you switch positions throughout the day?
Yes, I switch every hour. Also, when I have a meeting where I don't have to present my screen, I always make sure to switch to my phone and walk around. That's another very important, but often overlooked exercise.