Misogi
An important practice from the Shinto tradition, misogi-no-kokyu-ho may be translated as purification through breathing. Training is arduous, emotionally straining, and physically exhausting. Yet it is a unique opportunity to break through self-imposed limitations and egoistic personality defenses. With the intense stimulation of misogi, primal life force deep in the lower abdomen is activated and the potential to directly experience the root of one's being is at hand.
The above is an excerpt from an essay on misogi. Read the full text here.
Brooklyn Aikikai offers misogi training several times a week.