Our Fundamental Activities: Sitting, Standing and Walking

We have habitual ways of sitting, standing and walking that we need to come to recognize and understand.

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In sitting, we lift ourselves only from the pelvis up; this weight we are lifting is fully supported by an external object, the seat underneath us.
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In standing, we also lift the legs; moreover, the weight of the pelvis-torse-neck-head is not supported by an external object, but rather by our very own thigh bones.
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Walking is even more complicated. It is, in effect, standing on one leg at a time while also moving forward in space.

Physiologically speaking, sitting is the easiest of the three activities. But because we mis-direct our falling much more egregiously in sitting than we do in standing, and have far less variation, it is much more difficult to recognize and change our sitting habit.