You know what? "Being yourself" is a work in progress. Your self isn't a static "thing" that you keep inside you. It's a growing sense of what you can do, based on what you've done in the past. It's trial-and-error, and if you're open to making changes, then the errors are your teachers.
So, the advice "be yourself" was important. So was the advice, "You don't know until you try." And, between those two, I've gotten this far!