On the other hand, I grew up driving manual, as most people in Europe, and my first time driving an automatic I was rolling up to the car rental exit and I pressed the brake as hard as I usually press the clutch. It was not fun for anyone in the car.
Then over the next few days of road trip, everyone else in the car had their turn at driving and we all did it 2 or 3 times, so it became an inside joke.
The hard part to muscle-learn was to leave the left foot alone and just use the right one.