[The Japanese concept of] Kan Geiko: Rigorous training is one of the Do [forms of Japanese art] that deliberately takes place during the coldest time of the year. While it can be misinterpreted as an exercise in masochism, kan geiko is actually a form of "spiritual forging" — a quality commonly identified as one of the primary reasons for participating in the various Do forms. The Do value and cultivate a positive and indomitable attitude, the real motivation for training long hours with no heat in the dead of winter.
— H. E. Davey, Living the Japanese Arts & Ways