Way back in the history of the human evolution a critical and ”negative” thinking was necessary to survive out in the wild.
It could be about life and death if you took the wrong decision, so it was really important to evaluate all the risks that could appear.
So it i´s actually in our nature to think in this way write Angela Ahola in her book (Konsten att göra intryck) ”Translated to: The art of doing impressions”
Though you can built new neurological connections to think more positive todays neurological research shows, and that will do BIG changes in your life. We dont need to be aware of the deadly risks thats out there today in comparing to the past.
So to build a better life for us today we need to practice more on how to create these really important positive connections in our brains that supports positive thinking.
Here is a great practice you can do to building a more positive thinking, I did this through a course in 9th grade and I still use them!
Hope this can help you get some more positive thought! It have clearly helped me!