I picked this up from a book about reducing asthma symptoms. It's a breathing exercise that suppresses a cough when having caught a cold or flu. It works brilliantly.
It helps if you download an interval timer from Apple or Android. They are free.
Hold your breath for four seconds.
Breathe normally for ten seconds
Hold your breath for four seconds.
Breathe normally for ten seconds
Repeat the cycle for five or ten minutes. It may eventually brings up some phlegm. You just swallow it, it's nothing.
