If we could all get a handle on the material in this chapter, so many wellness things would come so much more easily!  We cannot underestimate the power of our thinking mind to transform our lives.  Read that sentence again - do not doubt it - you can literally change your life by changing what you think. 
   There are many aspects of thinking that this chapter considers and while they are all important, space requires some consolidation and paraphrasing here!  First, on a strictly physical level, we know that our thoughts have an impact on what happens in the body.  Thoughts connected to stressful events promote a certain combination of hormones and neurotransmitters to be more present than those associated with thoughts of a relaxing event.  That chemical soup then directs the actions and functions of our body.  Change the thoughts, change the hormones, change the action of the body.  Forms of biofeedback and neuro-feedback are used to help us use our conscious thoughts to impact our physical being.  On a more personal, practical level perhaps, imagine your alarm clock set for 5am and how your body feels when it goes off so you can be on time for work.  Now imagine how your body feels when 5am comes and you get up to be at the airport on time to leave for your Hawaii vacation.  Can you see that a thinking state of dread or boredom vs. anticipation changes how the body functions?
   One of the problems with thinking is that so much of it comes without our paying any attention.  We are bombarded with information all the time and we have to choose what to pay attention to and what to ignore.  Our previous habits and experiences play a big part in what gets noticed.  We may be in the habit of worrying about things.  We may be in the habit of having to be right.  We may jump to conclusions, have unrealistic expectations of ourselves and/or others,  take everything personally or confuse our feelings with facts.  These habits can be so ingrained that we can forget that there are other options - other ways of looking at or reacting to a situation. 
   Part of getting a handle on thinking is to pay attention!  Notice your thoughts - and give them credit only for being a thought.  Where do they come from?  Are they limiting your problem-solving skills?  Do you see patterns in what and how you think? 
   Another aspect of thinking is simply and commonly discussed as right brain/left brain thinking.  The differences in brain-side functions were discovered accidentally, really, in trying to help severely epileptic patients by severing the corpus callosum which connects the two hemispheres of the brain.  It was found that the brain sides control the opposite side of the body and, in general, the left side is the linear, verbal, logical one and the right side is the creative, non-linear, artistic half.  For our whole wellbeing, it is healthy to be able to use both sides.  If you have not seen the video of neuroanatomist Dr. Jill Bolte Taylor talking about her stroke, it is an excellent view of our 2-sided brains.  Here's the link:  Jill's 2 Brains  Even if you have seen it, it's worth seeing again!
   There are many kinds of thinking and certainly some thinking is required to get safely through most of our days.  But if we look honestly, much of our thinking is counterproductive, even harmful and mostly isn't even our own!  Our unconscious patterns of thought are one of our biggest obstacles to our whole health and enjoyment of life.  Start by paying attention.  Continue by sorting out what you begin to see.  Discard what doesn't promote your best wellbeing - yes you can! - and focus on what does.  Use meditation, guided imagery, lateral thinking, brainstorming to change and enhance your thinking state - and so change the reality that you experience.