this is true.
stand in the bathroom, alone enough that you can't hear anyone else in the house and they can't hear you, or, preferrably, completely alone. This is so that you won't be distracted, not because it makes things "scarier"... they don't need to be. You can do this any time, day or night, provided you have a quiet setting.
Look at yourself in the mirror. Give yourself a good look, and resist any urges to comb your hair, wash your face or anything else like that. You aren't trying to fix yourself. You're just trying to see yourself.
Think back to your earliest memories, happy, sad or otherwise. Remember who you were when you were a child of two, three, four years old. What did you want? What did you fear? What did you dream about? Now, stare your reflection straight in the eye, and ask:
"Who are you?"
Be patient with yourself. Ask again. For most people, they have a strong impulse to follow up the question with "You aren't me... so who are you?" Go ahead and say it if the urge strikes you. Just make sure you aren't drowning yourself out. The words are meant to help focus you towards looking yourself in the eye and seeing yourself stripped of conceit and white lies and presuppositions.
I discovered how to do this when I was a teenager, by accident. No one I know who has tried it, including myself, can keep it up for more than a minute or two without becoming very mentally agitated.