Dr. Robin's friend recently shared with her that, as a young child, she overheard her father say she had bad luck because she had fallen down, scraped her knee and then developed a nasty infection in the wound. That friend says she carried that negative message with her for years, subconsciously believing she really did have bad luck whenever bad things happened to her.

How many people are told they're shy as a child and then become shy as adults? How many people are told they're stupid as children and then grow up underachieving because they believed that message? Dr. Robin says what we believe often is what comes true. "What we believe is what we focus on, and then that's the thing that gets bigger," she says.

Those false message are like someone else's mail that was accidentally delivered to you, Dr. Robin says. Just as you would write "Return to sender" on the envelope and send those messages back to the post office, she says you should take the messages you were told throughout your life that may be holding you back and then delete them from the in-box of your mind.

"Get rid of it," Dr. Robin says. "Not in a way that you deny it and not in a way that you blame the sender, but in a way that you recognize that that message was not actually about you."