This might be more dramatic if I could cue the heavenly music in there, maybe some Josh Groban singing a pivotal note or something.
Suddenly I knew why the protag was doing what she was doing and why a seemingly minor character was doing what he was doing and how these actions could possibly weave the story into much better shape than it had originally started out. *takes another deep breath* My MC is literally screaming in my head because she already had her epiphany...she was just waiting for me to catch up and write it out for her.
Another way I define an epiphany is getting out of my "duh" moment. LOL
Have you ever had an epiphany while writing and how did that pan out for you?