Judging your work and finding a balance in your self-critique, not being too harsh on yourself but still being brutally honest, could be the most difficult problem to face as a creative. Creativity itself is easy in comparison, it comes naturally if you just leave the space and time for yourself to do it. Knowing which of your creative ideas are good and how they fit together is more like a complex math problem.
Or if not a math problem, it’s one that takes really good intuition that comes from years of experience.