Again, not much scientific backup here but I believe that electro-magnetic (file:///C:/Users/anand/Downloads/349-629-1-SM (1).pdf) current flows thru all living organisms and exercise, breathing and physical yoga, meditation, tai-chi, acupuncture etc. are all ways to remove any blockages in this flow. The Indian word for this flow is "prana" and the Chinese word is "Qi" which roughly mean "life force". A good teacher can literally see where your blockages are just by observing your breathing and posture. Some of the blockages can be caused by past traumas and if left unattended can turn into debilitating disease.