This phenomenon—winning or losing something in your mind before you win or lose it in reality—is what tennis player and coach W. Timothy Gallwey first called “the Inner Game” in his book The Inner Game of Tennis. Gallwey wrote the book in the 1970s when people viewed sport as a purely physical matter. Athletes focused on their muscles, not their mindsets. Today, we know that psychology is in fact of the utmost importance.~ Shane Parrish from, https://fs.blog/2020/01/inner-game-of-tennis/
Somewhere I saw a great interview with Gallwey. (Try TouYube?) Some of the insights from his work—for example, that psychology is critical to success in sports—now seem obvious. But 50 years ago, this was not only “not obvious” but was literally unheard of. (Insert my peewee-baseball story from the late 70s. *shudder*) There’s a lot more worth gleaning from Gallwey’s work. Positive thinking doesn’t work! Worse, it’s a hinderance as bad as negative thinking. *gasp* This insight is also 50-years old, but from my conversations with athletes, it doesn’t appear that it’s percolated as thoroughly.