Urasenke cha-no-yu is a direct offshoot of Rikyu tea ceremony.   The standard was set in the 16th century by Rikyu and was adopted as a method of training by the Samurai warriors who saw this as a way to cultivate calmness in the face of adversity.  There are accounts of warriors performing tea ceremony before a battle to center themselves and demonstrate their calm.   The prescribed actions of tea ceremony must be done with focused concentration and careful attention to each detail while being aware of each body movement.