I have changed my chair for a plyobox based on Core Balance Training video recommendation and this simple change immediately improved my body engagement while working at home at a height adjustable table. It is not only about sitting and standing but about many different positions.
Also, I have tried a bare foot shoes as I have noticed, that when I wear standard sneakers my back starts to hurt. Now I engage my toes much more and the core is working against the impacts, so my back is more protected and pain is not there anymore.
Those were small changes with minimal effort and budget and have huge impact for me. Now I am thinking about new ways to improve my life with minimal effort more.