The fool seeks happiness in the distance.
The wise man grows it under his feet.
James Openhelm
Emotional Thinking
How People Get Stuck in Inaccurate and Unhelpful Thoughts and Feelings

The human brain has three main parts. The upper section is the cerebrum, which contains the neo-cortex and is particularly developed in human beings, allows us to have complex thoughts, understand language, and so on. The lower section is called the limbic system and is much cruder and is also called the 'emotional brain.' It chiefly affects our feelings and emotions. The third part is called the brain stem and controls basic functions like body temperature, heartbeat, and blood pressure. It is similar to what can be seen in simpler animals like lizard so it is sometimes called the 'reptilian brain.'

Although they are crude, the simpler parts of the brain are fast and in emergencies they can override the more subtle but slower neo-cortex. You can probably remember a time when you have stepped out onto the road without looking properly and then instinctively jumped back onto the pavement before you had even been conscious of seeing the oncoming car or lorry. It was your limbic system that saved you.

When people are emotional in any way, the limbic system begins to override neo-cortex processing, literally making us stupid. If you approach someone who is upset and crying and ask them what the problem is, they will often be unable to manage more than a few clumsy words. It is only once they have calmed down and their neo-cortex has fully come back online that they can explain the situation clearly.

It is this impairment of the neo-cortex and its subtle thinking processes by the limbic that can set up a kind of feedback loop of thoughts and feelings. As someone feels increasingly emotional, their thinking becomes increasingly black and white and locked into one perspective. This crude thinking tends to increase their emotional arousal, which in turn further diminishes their cognitive abilities.

People with phobias might know a spider, say, is harmless when they are calm but be unable to recall that knowledge when they are emotionally aroused by fear.

Before they have learned to calm themselves down and recognize inaccurate black and white thinking for what it is, people who are feeling depressed experience this spiral, as they get increasingly emotional and adopt an increasingly fixed and categorical viewpoint, which is what causes the clearly untrue statements that people who are depressed sometimes come out with like "I've never been happy" or "There's nothing good in my life."

To feel better, people need to be able step out of these loops by learning how to calm themselves down and recognize their faulty patterns of emotional thinking. If you need any help doing this, a good therapist will help you learn these skills quickly and easily.