Quartz: The (lack of) science behind happiness and creativity.

... a positive mood is useful when first brainstorming, processing information, and coming up with as many ideas as possible—you don’t want to bring judgment into that, because it could stifle idea generation. But rigor is the key to overcoming obstacles and completing tasks—and good mood doesn’t improve problem-solving, which involves judgments that almost by necessity won’t feel good: critique and evaluation, experimentation and failure. The stress that arises from problems may be unpleasant but it also motivates us to complete tasks ...

Gotta take a lickin' and keep on tickin' ... to paraphrase a famous psychologist, you cannot make your critique personal, pervasive or permanent. Those three aspects are death to generating creativity. At that point you're handicapping, not helping.