by tapping up and down your sternum or chest you increase the number of white blood cells to defeat your cold.
Interesting, I have been a heavy smoker for over 10 years, and I battled lots of bronchitis and upper respiratory infections as a teenager. I do this (tapping) every time I feel a little tight or pain, or spasm coming on, and in fact alot as of late, even with no pain or tighness. My last cold went away way faster than normal. Interesting.