Sitting is not a still activity
Our bodies are designed to move - even our breath brings movement into our bodies. But we often think sitting is a static position. Our bodies are really an unstable dynamic equilibrium system - just like bikes are. Just image if you had to balance on a bike without moving? But once you get cycling, balancing is so much easier. So if you have in mind you are balancing when sitting this may help ease tension in your body. This also applies to standing, ideally our bodies work best if there is a little movement in our ankles, knees hips and top of our spine even when we are standing 'still'. These wobble cushions can help you with this process in sitting (and standing). Applying the Alexander Technique of freeing your neck helps bring about freedom in our main joins and so can help with this balancing act . Here is a link for a wobble cushion https://www.integratinghealth.com/single-post/2016/10/05/