Your problem is being cold at work? You must have a chair-based job. I sorta envy you. It’s better for your body to be standing and moving as much as possible.

Yoga ball in lieu of chair?

one of those desk riser gajobbies that people tell their employers that they have back issues to obtain?

or just bring/leave there a thicker fleece/wool sweater, hat, & socks.

really, hat & socks can be surprisingly effective.

so too can be once every half hour doing three or four 5-second heel squats.