I am trying to get familiar and eased with the practice of breathing from the lower portion of my abdomen. When this technique seems to go well, it is very calming for the mind, and there is more of a sense that I am truly concentrating by allowing myself to breathe as I will- instead of breathing from the upper chest, which seems to require more effort and seems forced. Any input on how to proceed? My teacher is unavailable.
In Vajrayana there are special techniques using the breath and energies of the body, some of which involve locking a union of winds in that area below the navel where the central channel begins it's ascent. This is known as the "small vase" breath. It is however quite another thing from the simple tan-tien breathing you're describing. However it has a very powerful purifying effect and calms the mind considerably. It therefore is known as "the yogi's best friend". But you probably want a Zen answer, which I can't comment on!