|Japanese kids practicing taki-shu-gyou 滝修行|
This kind of cold-induced chi training has often been used by martial artists to strengthen their bodies and calm their mind (in particular before a fight). Famous Brazilian jujitsu master Rickson Gracie demonstrated in a documentary (the Choke) his style of cold-induced chi training (check my previous Martial Art workout post here).
Without going as far as Master Gracie, a veteran meditation practitioner can try practicing half-naked meditation during cold weather, perhaps immediately before taking a warm bath or shower. It is a good way to build a strong body/mind and to prevent common colds. Just remember: Concentrate....and don't shiver! Can you see which of the Japanese kids is shivering?