We create our own realities with the millions of thoughts that are constantly occurring in our minds. So, if the thoughts are negative, the perceived reality in which we live will also be negative.
If your thinking patterns have always leaned more towards negativity, it can be difficult to imagine an alternate way of looking at your life. However, it is possible to turn it around. Positive thinking is a conscious effort, and may be especially challenging if your outlook is largely pessimistic.
Charles Donoghue prefers to call this Mega thinking however and is a much more effective way of creating the right thought process in your mind.