Prepare for brilliance.
The fallacy is that only certain people experience it, and the rest of us don't. When really, I could be drunk and going to the washroom and have a brilliant idea - I mean, a friend could be drunk and going to the washroom and have a brilliant idea, and come back to their desk and write it down, and in the morning wake up and say "yes! That's true!" OR they could wake up and say "yeah, I remember having this brilliant idea...what was it again?"
Brilliance is available to you, just as it's available to every living person. Do you choose it?
Begin practicing your brilliance. Prioritize it. Build your life around it. Be prepared to interrupt whatever is happening. Cut off your friend mid-sentence. Keep a notepad and pen nearby, in your bag, at your nightstand, open to the next empty and anticipating page...
...it is about to happen again, at any moment. Have you made room in your life for your own brilliance?