I decided to finish every normal 'hot shower' with a blast of totally cold water, after reading a book by an old healer by the name of Jethro Kloss. Anyway, I am a bad asthmatic, and used to get sick around 6 times per year. When I got sick it really affected my chest, with huge amounts of mucous, and real bad asthma.
Now I rarely get sick (it boosts the immune system as well as circulation), and if I do it's usually just a mildly sore throat. I wish I could better explain the massive difference this has made. Even if you feel sickness coming on, a cold shower will often stop it in its tracks.