I noticed in the book that using one's chest more for breathing was a sign of improved posture.
In many yoga/meditation related practices however, this seems to be a bad thing and stomach breathing is considered most beneficial, as a way to use more lung capacity, relieve stress, etc...
See, for instance : http://beginnersmeditation.info/blog/understanding-embryonic-breathing-part-1
What is your take on this? Should I aim for chest- or stomach-breathing?