Thank you, Dean Ware, for the simple explanation:
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.