When positive thinking is seeing bad situations in a favorable light, you can look for the good and make the best of life’s terrible blows. That’s OK.
The problem with positive thinking is the implication that if things don’t go right, you’ve failed yourself. That you’ve not believed in yourself enough. That you should blame yourself because there’s nowhere else to go.
Positive thinking so isn’t a temperament that works when things aren’t going well—that’s the real test as to whether a mindset holds up.
What you need is an attitude that radically embraces reality. It allows you to face the possibilities of negative encounters and not shun away from them. It lets you honestly appraise your circumstances.