He is just too stubborn to die and though he struggles to motivate himself, Tyson simply doesn’t stop once he starts. He keeps going until he has nothing left to give.
As much of a strength as that can be, it causes Tyson to take far too many beatings that forced him into needing that iron-will to survive. If Tyson could ever learn not to say die, he wouldn’t be in as many situations where he very well could die.
His talent for picking himself up, though admirable, would be entirely unnecessary if Tyson didn’t keep putting himself in situations that knock him to the floor.