Weirdly enough, though, it's outside of the Octagon where he's suffered most of his punishment.
When he gets into the cage, he's usually the dominant force, but it's getting ready and prepared for the fights that usually hurts the Russian the most.
How, you ask? Well he's always openly admitted he struggles to make weight for fights, and that was on show when he was preparing for his final fight against Justin Gaethje at UFC 254.
The Russian has often struggled to maintain the weight limit of 155lbs, which is required for the lightweight category. He undergoes gruelling sessions of weight cutting in order to ensure that he fulfils the requirements.
In the past, the Russian has admitted to suffering from seizures whilst attempting to make weight. It happened to him ahead of the Conor McGregor fight, and a proposed bout against Tony Ferguson ended up being cancelled due to the struggles the Russian had.
Back in December of last year, Khabib posted a video of his weight cut prior to his fight versus Gaethje at UFC 254 and it truly does make for hard viewing, as can be seen above.
He's seen profusely sweating while losing the last few kilograms on a bike before being wrapped in layers.
The Eagle loses a great deal of strength to the extent that he is helped to his feet by his trainers.
The entire weight cutting is brutal and it makes for tough viewing, and this was only the last few kilograms. So one can only wonder how gruesome it would have been to lose 40 pounds, which is how much he reportedly cuts before fights.
However, not long after his weight cut, Khabib defeated his American opponent by submitting him with a triangle choke in the second round to defend the UFC lightweight championship.
After the fight, The Eagle announced his retirement from MMA. He finished his career with a perfect record of 29 fights and 29 wins.
However, he is still involved in the sport as a promoter, having bought Gorilla Fighting Championship for $1 million and renaming it as Eagle Fighting Championship.News Now - Sport News