The Death of Positive Thinking
The bad news is that Positive Thinking, Visualization and similar techniques don't work, because, for your brain, thinking of having fulfilled a wish or accomplished a task doesn't make any difference from having fulfilled or achieved in reality. And, after all, you've already your dose of serotonin.
The good news is that the phycologist who has demonstrated the negative correlation between positive thinking and successful achievements
Check out her book Rethinking Positive Thinking.
It’s worth a try.
https://www.clearerthinking.org/single-post/2017/03/14/Want-to-change-your-habits-Try-this-simple-tested-tactic