This exercise is pretty easy to describe: just take a cold water shower!
If this sounds really ridiculous… GOOD! This means that you have a perfectly healthy rational mind.
But the reason why I’m recommending this to you, it’s because cold shower have been used in some cultures as a real good exercise for purification, curing diseases, revitalizing and so on including India and China. Traditional Chinese medicine and Ayurveda (Indian medicine) have long used cold water therapy to heal ailments. In Russia, they actually swim in cold and sometimes frozen lakes (not only showering) for good health. It’s called Ivanov Therapy.
It was also a purification practice done by practitioners of Shinto (Japanese religion) called Misogi where they would take cold water showers before the sunrise and after the sunset every day. This was a purification ritual on a spiritual level.
More information on the video!