So a penalty taker should be very precise about their routine, and the desired outcome.

They should give the brain clear and specific positive things to focus on, such as "I am going to walk at slow pace, then I am going to hold the ball in my hands, then I am going to have a look around, then I am going to strike the ball with power and accuracy like I did against..."

Once we are specific about what we want, the brain will find a way to make it happen. Trust yourself.