Tomorrow, I plan to give a meditation concerning this. Basically we can reflect that this body is composed of the Four Elements - earth, water, wind and fire. Then we can trace it back to how it was created, came into being, and how it depended on the Four Great Elements for that. How each moment of our life is dependent on the Four Great Elements internally and externally. The internal Four Great Elements and the external Four Great Elements, so we start to see that this body is not really ours to control, but it arises dependent on other things beyond our total power to control.
Earth: in order to survive we need to renew this body with the earth element - food. We need to breathe, air element, moment to moment. We need our blood and other fluids - water element. We need the fire element; we need to have the fire element from the sun, we need the fire element for digestion. This starts to make us realize that we are interconnected to everything else and this breaks down a great deal of this sense of ourselves being separate from everything else. Cause and effect, this body came about through causes, and unless the causes continue to be replenished, it ceases to exist. That's a brief answer, we'll go into more detail tomorrow on how you can expand the Four Great Elements reflections to consider other objects, etc.