How Do I Get from Here to There?

I am having such a hard time changing my thoughts. For the past few years it seems like I default to looking at the negative in every situation. I am having a hard time flipping the script and thinking positively. I try doing mantras, and manifesting, but it just feels so fake. How do I get from being a negative nelly to being a positive patty?

I know my thoughts create my things. I’m find myself stressing out over my negative thinking which then creates this downward spiral. Any tips on how to get over this?