So why have a whole tutorial just on this? Two reasons.
First, breathing is much more important in martial arts animation than it is in almost any other field. Control and timing of breath is so fundamental to many arts that the difference between a perfectly executed technique and a complete flub can be made by exhaling at the right time. It all has to do with the effects that the contraction or relaxation of the diaphragm can have on all of the other muscles of the body. But that's not the reason I decided to dedicate a tutorial to breathing.
The second, and far more important, reason is that breathing as an action isolates several principles of animation which can be profitably applied in a wide variety of different situations.
So, on to breathing!