Instructions to meditate usually begin with the simple invitation: Take your seat. It sounds innocuous enough but it's important. I'm told of people who meditate while lying in bed or in the ad breaks, but I'm personally doubtful about how possible that is. Sitting is a key to the whole process. Get this bit right and you're well on the way to learning how to meditate. I think.
Most of the time, most days we are quite unaware of our bodies. They are just there, moving us around, providing a handy receptacle for food and drink and giving us something to park our glasses on. Our bodies do their thing automatically and we don't have to think about them at all except when they hurt or itch or make embarrassing smells or inexplicably fail to do exactly what we ask of them. It's as well that we don't notice our bodies most of the time; after all, the mark of a good servant is to be unnoticeable. During meditation, though, we are going to be completely aware of our bodies for quite a period of time, and we need to sit in a way that makes that possible. We are also going to be still for longer than the body is normally used to, so we need to be seated in way which minimises pressure points and allows us to make subtle adjustments to our posture when it might be necessary. Our bodies are -mostly - reliable servants, but for much of the day they are also cunning and at times tyrannical masters, telling us when to move or eat or fidget or scratch or sleep. The mastery the body has over us happens mostly because we are unaware that it is the body that is in control. For this period,while we are seated, we are going to take complete power over our body and the body doesn't much care for that.
Our bodies are as seamlessly part of us as our minds and spirits and so connected that what we do with our bodies will necessarily affect what we do with the other two parts of our personal trinity. Of course we acknowledge this fact whenever we kneel for prayer or stand when a visitor comes into the room. In meditation we assume our seat, telling the deepest parts of ourselves that we are here with a purpose.
The way our bodies function can't be completely explained by any doctor, no matter how big an anatomy textbook s/he may have read. They have mysterious but quite predictable patterns of energy. They have rhythms and flows and pathways and junctions and storage points for energy that may all be affected by the way we are seated. We want all this stuff to work for us in the most helpful manner, so we choose our place and manner of being seated with care. Of course, the Eastern books all recommend sitting cross legged on the floor, but unless the session is going to become merely an exercise in pain control and a short one at that, I'm going to sit on something. It's taken a while of experimenting and thinking about it but I have it sort of OK now: a way of sitting that I can maintain for sufficient time, and where I am as unencumbered internally as I might possibly be. So, take your seat. What's next? Easy. Breathe. We can all do that.