Just like dementors from Harry Potter your Inner demons suck the happiness out of you, leaving you with sadness, self-doubt, and anxiety. Instead of letting your demons control your life, you’ve got to tame it and keep them in control. Or else your life would be consumed with negativity.
When your demons try to pull you down to negativity the best thing you can do is to concentrate on your happy memories. Then your inner demons would ultimately get tired of making you sad.