Much has been said and written about the power of positive thinking. I, too, subscribe to the idea, along  with a healthy balance of the negative (Barbara Fredrickson extolls a 2:1 balance.) Here is what Stephanie Vozza writes as 5 positive results of being negative:
1. Negative thinking helps you avoid failure.
2. Negative results can strengthen your focus.
3. Negative moods can produce better teamwork.
4. Negative thoughts provide a healthy balance.
5. Negative reminders can keep you grateful.
I think she’s onto something.
http://www.fastcompany.com/3038199/the-positive-results-of-being-negative