Passimistic thought - How much they effect us ?

Absolutely right!  Just like we are what we eat, we are also what we think.  At any given time, we are one thought away from feeling confident, happy, loving, connected...or...fearful, sad, hateful, lonely.  We just have to think it and we feel it. 

How many times have you had the blas, only to hear, see, read, etc. something that changed your thinking, like a phone call with good news, or a test you thought you failed and didn't.  Or, maybe it was something on a commercial that touched you and stirred up positive feelings about you or someone else.

There is a lot of research on your question that proves you are right.  So feel good about yourself and your reasoning skills.  Some call that critical thinking - a good thing to have so you can stay the winner you are.  Just remember, you are only one thought away from how you want to feel... just have that thought!

Obviously, thinking positively helps in succeeding.  On the other hand, a cynical view of circumstances is a defensive stance, and forms the basis for our safety industry.  So pessimism is a valid function of human thought.

   Put another way, dead heroes are optimists and live cowards are pessimists.  Bull traders versus bear traders in the markets.  Each view has its advantages and drawbacks.  False or unfounded optimism and positivity is just as deadly or harmful as negativity, maybe more so in some circumstances.

    I can't justify the tagline you quoted as a useful function of pessimism.  Why adopt a philosophy of being a loser?  That's a soul killing viewpoint.  The highest function of pessimism is to allow one to prepare for any and all problems that may arise in the unknowable future in any enterprise, and allow for a greater chance of success.

   As far as the philosophy that "the thoughts we think are very much responsible for what we achieve"... I have to agree, with reservations.  Sometimes it's the thoughts we don't think that allow us to accomplish something.

People with pessimistic views of life are usually losers and the optimistic ones are the winners.

    That reminds me the difference between the Republicans and Democrats.  Sorry to say, just my objective observation.....

The concept in classical physics, which is part of the second law of thermodynamics, applies here.  Entropy is a force which applies to all things and animals on this Planet.  Situations, objects and live creatures become more disorganized with time.  Deterioration and demise is the universal standard for this Earth.  Everything and everyone is destroyed with the passage of time.  liOptimisim is nice, but it is not inline with reality.  Even the law of "survival of the fittest" is unpleasant.  If you believe the worst about people; you will be correct most of the time.  Reality sucks but the truth is what it is.                            

yes,when we have pessimistic thoughts,then things will go wrong,but when we have optimistic views,a solution can always be found..plus,we live longer when we have happy thoughts then when we have sad ones