These could be physical characteristics or mental strengths, but whatever the positive, the decline can come steeply. That shot would have taken many fighters out.
After considering retirement just three months ago, Brook showed he still has a future in boxing with an impressive debut at super welterweight and a return to winning ways.
Against Golovkin, Brook had jumped up two weight classes against perhaps the hardest puncher in boxing, and did not disgrace himself at all.
Brook takes on dangerous Belarusian Sergey Rabchenko in Sheffield on Saturday
Although both fighters' stars have faded since Brook won his welterweight crown, Khan and Pacquiao both remain lucrative possible match-ups. To see all these people turn out, get myself in shape, my life could not be any better now and I've not hurt my hand or anything, so I'll get back in the gym.
Brook's smarts saw him impressively beat American Shawn Porter in 2014 to join Manny Pacquiao and Mayweather as welterweight belt-holders.
Judgmental whispers about Brook's ring career have refused to die down, despite the fact the former world champion is looking for a fresh start against Rabchenko. Brook has 53 rounds on his opponent.
Due to his alliance with Ricky Hatton, Sergey Rabchenko has fought many times in Britain before, but the Belarusian has never achieved significant success. Rabchenko has a good record at 29-2, but is a way off the elite champions of the division.
Who is favourite to win?
Those injuries are a major concerns considering Spence Jr targeted Brook's right eye last May, before breaking the left one. One broken eye socket is a disaster, but to suffer consecutive breaks in fights is extremely troubling. Concerns about Brook's ability to compete and the sheer effort of cutting down sparked the move up, and both fighter and coach, Dom Ingle, are confident the step up will solve past issues. Some aspiring money-makers may be tempted by such odds.
"We need to talk about weight and make it happen".
Watch Brook's comeback in the super-welterweight division against Sergey Rabchenko on Saturday, live on Sky Sports from 7.30pm.
A good undercard supports Brook vs Rabchenko, led by Gamal Yafai meeting Gavin McDonnell in a domestic super bantamweight showdown.
But there was no such injury drama on Saturday night, as "The Special One" returned to the win column in his native Steel City and claimed the 26th knockout of his career without breaking a sweat.