I do pulling exercises (back muscles), reverse crunches or leg raises (lower abs), and hip thrusts (glutes)! Also: stretches to open up the chest, neck stretches, lunges to stretch the front hips (hip flexors).

I try to do these every day or every other day. It doesn’t take much time. I’m not trying to build anything. It’s about good habits and maintaining strength in muscles that tend to weaken with prolonged sitting. All I really need is a resistance band - which has the added perk of being able to bring it on vacation:)