Thoughts and emotions are pathways, they become a habit and you need to work to retrain your brain to ‘not go there’. Its like quitting smoking or anything else, it takes work. Its like learning a new emotional language. It will take a while and you will have to make a solid effort to avoid thinking and dwelling on the negative but it can be done.
Don’t watch ‘downer’ movies or listen to much anger, don’t watch Jerry Springer and ease up on Fox news, ease up on heavy metal and dark music. Take in uplifting stuff, positive messages, motivational things. Get lots of exercise, do other things that will make you better, take a ceramics class or photography. Stay busy, don’t sit still, whenever it creeps in get up and do something else.
Yea it feels weird going out of your way trying to be happy, at first it feels like some sort of con of a joke, like your trying to trick yourself. Yea I miss my gothic music and my Slayer and the horror movies and all that but when you get all that out of your head (garbage in garbage out)
Listen to classical music, go for walks, volunteer at a homeless shelters, go out of your way to be nice to strangers, work at it and after a while your not faking it and one day you realize it’s become a self fulfilling prophecy.