Such behavior is natural when you don't make a rue assessment of yourself and walk in direction unsuitable to your basic instincts. Just one needsto first decide what are his best klatent interests, aptitudes and talents. He will definitely suceed and never show signs of pessimistic or self defeating behavior. 

" Know thy self " is the old adage. I believe in it. Identifying your strengths and weaknesses  is essential. And after identifying your strengths and weaknesses strengthen your strong points further and strive to work on your weaknesses to convert them in to strong points.

very good posting thanks

Negative thoughts are not that difficult to wipe off from the mind provided you have a strong will to Win. A life without negative thoughts is a blissful life, Before that you stop thinking about bygone bad incidents. That is one has to live in the Present. Then Optimistic attitude naturally develops over a period.

Negative mental attitude is an adamant wall on our way to success. We have to destroy it at its foundation to move ahead towards success. 

Negative thoughts will create in people that they are incapable of doing anything. This is a dangerous trend that has to be nipped in the bud.