By 1974, 26-year-old Bobby Orr had no business being anywhere near skates.
Orr, the great Boston Bruins defenseman, should have, by all rights, retired because of knees ravaged by injuries and pain.
But Orr pressed on, leading the Bruins to the 1974 Cup Finals.
The knees got progressively worse, even after Orr signed with the Chicago Blackhawks as a free agent. Unable to face the fact that his career was winding down, Orr kept putting himself through hell in order to play hockey.
Finally, in late 1978, just 30 years old, Orr tearfully retired.
"It is clear that I can no longer play hockey," Orr, scarcely able to speak because of his emotions, said at the press conference.
By the way, the photo above is Orr in his Team Canada uniform, taken before the famous 1972 Summit Series vs. the Soviets.
Orr didn't play in that series, due to—you guessed it—a knee injury.