Personal Development Involves Only Positive Thinking

Positive thinking is an important part of personal development, but it is not the be-all and end-all.
When it comes to developing new habits and life skills, optimism is essential. If I believe that the world is out to get me or that my issues are permanent, it will be extremely difficult to change them.

Understanding that you CAN make any change you desire, as well as being patient with the process, provides you with the attitude required for change.

But, aside from positive, there is another important aspect of personal development that requires setting objectives for yourself and following at least a loose strategy for how you intend to attain them.

Personal development does require positive, but it must be accompanied by an action or you will never see meaningful progress in your life.