It's difficult for a professional athlete to decide when to retire.
It's painful for us, the fans, to watch our heroes stick around for too long and lose time and time again in devastating fashion.
However, it's hard for an athlete to just walk away from a sport that their life has revolved around for many years.
For those competitors who achieve greatness in their respective sports, it's even more difficult to let it go. Imagine going from being one of the best in the world at something, to completely irrelevant.
Sounds like a tough blow to swallow, no?
In mixed martial arts, we have seen many a fighter stick around for too long and it's always a sad sort of affair.
You see them being interviewed about their next fight and they always talk about how they're finally back in shape and ready to make a run towards the title again.
In your heart, you hope that they can pull it off, but in your head, you know they almost definitely won't.
While I do think that fighters should retire once they clearly have nothing left to give the sport, there's something deeply respectable about a guy who doesn't want to let go of his dream.
Let's take a look at the 20 worst fighter declines in the history of mixed martial arts...