Yeah the brain is wired to be more negative as it was needed more to save our lives from animals. When we think negative our brain thinks that thought is important so it keeps replaying that thought. Sadly this can lead to depression.
Various things like exercise, meditation, laughter, hugging and positive thoughts help to break the cycle of negative thought.
We should be taught in school about the basic understandings of the brain and it’s affect on our psychology. Methods for well being and good mental health. Instead our brains are becoming over stimulated with bullshit and bad foods. It’s no wonder that suicide and depression is on the rise amongst kids. Anxiety med use is overtaking depression drugs for the first time.
One last point meditation is excellent for negative thoughts, depression etc. However different meditations work on different parts of the brain, they are not all the same. You have to find a meditation that works on the part of the brain that is causing negativity or an issue. TM works on the front part which helps to treat negative thinking.
The Amygdala deals with fear and anxiety which is at the back of the brain. I think mindfulness deals more with this.