You walked through a door this morning. Probably a dozen already.

Michael Phelps, the greatest swimmer of all time, didn’t walk through doors without using them, unlike the majority of people. Now he unquestionably had the talent. He also had a work ethic nobody could match. But his biggest edge was between his ears.

Before big competitions, he used a simple trick to turn negative self-talk into positive language. It's known as the doorway method. Here's how it works.

Every time you walk in or out of a door, say one useful, positive thing to yourself. Something you want your brain to believe. It could be as simple as, “You got this.” “You are built for this.” Or “Focus on the positive.”

Now count your doors. Bedroom, bathroom, kitchen, car, office, conference room. Most days it's 50 or more. That's 50 chances a day to repeat the message you want to hear.

And your brain listens to repetition because it believes what it hears most. So when you pair a message with a cue like a door, it starts to stick.

Phelps trained his body in the pool, but he also trained his mind through every doorway.

So today, copy the greatest swimmer of all time. The next door you open, say something good to yourself.