"…There’s something called 'experience-dependent neuroplasticity,' which is the continuing creation and grouping of neuron connections in our brains that take place as a result of our life experiences.
Neuroscience teaches us that neurons that fire together, wire together. Donald Hebb, a Canadian neuropsychologist, coined that phrase back in 1949. What this means is that whenever we think a thought or have a feeling or physical sensation, thousands of neurons are triggered and they all get together to form a neural network.
With repetitive thinking, the brain learns to trigger the same neurons each time.
So, if you keep your mind looping on self-criticism, worries, and how nothing is working out for you, your mind will more easily find that part of your brain and will quickly assist you in thinking those same thoughts again.
This shapes your mind into greater reactivity, making you more vulnerable to anxiety…"
more: How Complaining Rewires Your Brain for Negativity & How to Stop