Excerpt re: Breathing
What is meant in the classics by “energy” is the breath. Taiji Boxing particularly emphasizes the breath. It is considered that, throughout the practice set, breath-assisted movements will always be performed correctly. It says in the boxing classics: “Use mind to move the energy… Use energy to move your body.” Also: “The mind makes the command, the energy is its flag, and the waist is its banner.” Breathing in Taiji Boxing is a bridge between body and mind. When practicing, focus your intention on the breath, “nurturing it with integrity” and never making the error of acting in opposition to it [i.e. inhaling when you should be exhaling, etc.]. If you can breathe with smoothness, you will get the movements of your body to be led by the breath. Between passive and active moments, between contractings and expandings, all is linked by the breath, and you will be able to move with a rounded smoothness.
In other boxing arts and methods of exercise, it is not understood that breathing should be given extra consideration and should aim for smoothness, though the worry that working against the breath will be inferior does bring understanding to some. If you do not understand the role of the breath between the body and mind, breathing will just be breathing and movement will just be movement, mindless and unguided, and again there will be no effect worth speaking of. It is the breathing that makes Taiji Boxing superbly unique.
more at https://brennantranslation.wordpress.com/2014/11/30/the-taiji-manual-of-...