If you want to train musicians, you need to learn how they train goalies.
Similarly, if goalies want to improve their game, they need to learn what musicians do.
There are important points of departure; musicians can’t take the athlete’s ass-kicking attitude too far. Just try going out with an “eat my dust, you chuckleheads” attitude and play Massenet’s Meditation in a believable way. Good luck with that.
But as similar as musicians are to athletes, that similarity is greatest for goaltenders in any sport. I know this seems like a weird parallel, but it’s true. All of this “mental practice” and “centering” stuff that musicians are just now discovering is stuff that those guys have been doing since the 1950s, over and above even other athletes. They are in fact so far in advance of other athletes and performers that the rules of the game have been altered to keep them from being too overly dominant, precisely because they have been taking the mental aspects of their very mental arena seriously for four decades.