The mind body healing system in the body works quietly, almost automatically in the background to reduce inflammation, fight off infections, repair wounds, renew tissue, organs and bones. However, our thoughts and beliefs play a major role in our how our body operates at a biological and biochemical level, and whether they are allowing this forever-healing system to do it's job or not. Central to understanding the mind body connection, is knowing that our brain is easily fooled. It doesn't know the difference between what is real and what we simply imagine. So as our 'cells eavesdrop on our thoughts' (thanks Deepak Chopra), our body merely reacts at a biological level.
Our mind is constantly comparing things that come to us through our senses with everything it has stored from our culture and categorizing it into two categories: "this is good - it will help me thrive so I can rest 'n digest" OR :this is bad- I need to survive so let me pull all my resources away from usual body functioning to take care of this threat". When we've assessed that something is not a threat, our body hums along like a well oiled factory manufacturing antibodies, healthy hormones and cells. Awesome!
However, when our central nervous system is activated by fear (this is not good for me, I need to survive) - the usual renewing and healing processes of the body slow down while blood is preferentially diverted to take prepare our bodies to freeze, flee or fight - in other words, survive the threat. This is perfect if we really are being attacked by knife-yielding-man that our ever wise body recognizes that taking care of this threat is way more important than producing antibodies or digesting food. But if we're just in a state of chronic distress - let's say we're constantly imaging there is a knife-yielding man after us, then our biology and our mind body healing system is being constantly hi-jacked by health-eroding hormones that shut down the body's usual processes to continually deal with this apparent threat.
Our body is made to handle two kinds of stresses:
but it's not designed to handle chronic long-term distress that disempowers us.
Let's put it this way. You can fly an airplane off track for 5 minutes, or even 50 minutes, but if you fly off track for hours and hours - it's a problem. The same applies to chronic distress.