The Power of Positive Thinking

Psychoneuroimmunoendocrinology — yes it's a mouthful!! More simply, it's the science of how the mind, nervous system, immune system, and endocrine system all interact and affect the health of the body.
You've probably heard the phrase, "as a man therefore thinks in his heart, so is he" -- the underlying principle in this case being the power of the mind over the physiology (the quote also having other applications as well). Years ago while doing some studies I came across a claim which said, "nine-tenths (9/10) of all disease begins in the mind," which appears to align with the aforementioned theory. But I wondered, "how is this possible?" Well, in a nutshell, and after much more reading I discovered, "the body's primary stress management system is the HPA axis. The HPA axis responds to physical and mental challenge to maintain homeostasis in part by controlling the body's cortisol level. Dysregulation of the HPA axis is implicated in numerous stress-related diseases, with evidence from meta-analyses indicating that different types/duration of stressors and unique personal variables can shape the HPA response" (https://bit.ly/2Fm5yDm). And otherwise noted, "the hypothalamus receives feelings from the amygdala. The hypothalamus then uses the endocrine system to convert feelings into emotions through powerful chemicals, called hormones" (https://bit.ly/3jvjytz). 🤓‼️
So what does this actually mean? It means that the power of the mind in thinking can have a significant impact on the production of hormones. The hormones affected can be almost anything, from the growth and repair hormones , the stress response hormones , and even the "destruction" or "death" hormones. How serious can this influence of human thought on the body get? Well, there are astounding stories of individuals, both women and men, who SO believed they were pregnant that they began to experience physical symptoms within the body, swollen bellies and even breast swelling, only to find out later that they were not actually pregnant (not surprising for the men in these scenarios). It is a condition called "pseudocyesis" (aka: false pregnancy). It stands to reason then, that the impact the mind and thoughts have on the body can be nothing short of extraordinary! 
If the above is true, think how much of an impact can be made by simply thinking, "I am fine and healthy," or the converse, "I am ill and dying". Whatever the thoughts may be, the hypothalamus, will cause the body to come into line with the thinking!! That's not just opinion, that is verified science speaking.
So the next time a negative thought comes to the mind, it may be especially beneficial to stop the thought in its tracks and think a positive thought instead!!  [IMPORTANT NOTE: This of course doesn't mean that if an individual is bitten by a deadly snake, they should simply think themselves well, (although it certainly wouldn't hurt, I'm sure)! So, in addition to positive thinking, reason also says to use common sense too. ]