One of the fiercest boxers who ever lived–a man whose powerful body time has softened, but in its place left perspective–recently said: “Each man kills the thing he loves.” It’s simple quote, very memorable, and one anchored in fact.

Looking over many notable figures from history, the knockout blow that bumped them from their perch came not from a rival, but from somewhere less obvious.

For at a certain point in these journeys, something very profound happened. The fire burning inside them, the one that once compelled they fight on flickered. Maybe the flames dipped just for an instant. Not so much that anyone on the outside might notice. But a second of shadows where there had always been light was enough time for something else to work into its place.

Possibly for the first time ever, these champions questioned whether or not what they had always wanted, was worth it. And that second guess was the first step towards the end of whatever empire they had constructed.

And so they killed what they loved, not with acts, or neglect, but with their beliefs.

Afterward, maybe the flames roared back smartly, burning as bright as before. Many empire builders rise and fall several times. But the voices of self-doubt now waited at the perimeter for them going forward, like a fire extinguisher ready to snuff the flames forever.

That quote was from Mike Tyson, and it described a lot more than his own boxing career. Ultimately his most cunning adversary proved to be himself.