Try making a habit of using positive affirmations, eventually you will have trained your brain to replace negative intrusive thoughts with positive affirmations

I also think that a good thing for me is some form of distraction where if you can tell they are coming you can find something else to concentrate on. Another thing you could try is journaling where you can just write the thought(s) down and then try to redirect the focus somewhere else

Find that one thing that you find peace on

i like to remember that they’re just thoughts and they can’t hurt you. you’re the one in charge, not your thoughts. even though i know it doesn’t feel that way sometimes. also, intrusive thoughts don’t make you a bad person. ive been told to just let the thoughts pass without trying to stop them. i think that’s a mindfulness technique? so if you think that could be helpful maybe give it a shot.