Thank you, Dean Ware, for the simple explanation:
"Neurons that fire together wire together.
To oversimplify: Our brain cells communicate with one another via synaptic transmission–one brain cell releases a chemical (neurotransmitter) that the next brain cell absorbs. This communication process is known as “neuronal firing.” When brain cells communicate frequently, the connection between them strengthens. Messages that travel the same pathway in the brain over & over begin to transmit faster & faster. With enough repetition, they become automatic. That’s why we practice things like hitting a golf ball–with enough practice, we can go on automatic pilot."
So if we get used to feeling bad about others, feelings of
jealousy, etc, we increase those feelings.
On the other hand, if we work and practise gratitude, self-love, those feelings become stronger too.
You have more power to change your brain for the better. See
it like a muscle; the more you work it, the stronger it becomes. If you feel
that you tend to be negative, don’t ostracise yourself, because this comes from
survival.