"There are no two words in the English language more harmful than 'good job'."
That being said, my first pick is Damien Chazelle's Whiplash (2104) staring J.K. Simmons as an ends-justifies-the-means music teacher at a prestigious New York music school, and Miles Teller as the student who aspires to be one of the greatest drummers ever. What follows is a tense, complex, uncomfortable examination of the demands, sacrifice, and drive required to be great. It is a challenging movie, as it illustrates the delicate relationship between a teacher (or coach) and their student, and how toxic it can become under the wrong circumstances. It doesn't shy away from showing the psychological consequences of toxicity. J.K's character believes he is pushing people "beyond what is expected of them" otherwise he is depriving the world of the next great musician. His demanding, obsessive approach is as effective as it is problematic. This film shows taking this particular path to greatness can essentially ruin your life.
Whiplash is definitely a movie to check out if you have aspirations of becoming world class at anything, really.There are definite parallels between this movie and fighting. Floyd Mayweather, for example, didn't have a much of a childhood, never worked any part-time jobs, and dropped out of school in order to become the best boxer alive. You don't necessarily have to approach coaching in the psychologically damaging way that J.K Simmons does in Whiplash, but there are definite sacrifices to be made.