In a perfect world, any athlete would love to retire from their sport on their own terms rather than an injury.  Unfortunately not every athlete gets that opportunity and careers are cut short or ended by injuries.

On Friday, one-time Rocket Richard winner and two-time Olympic gold medalist Rick Nash retired from the game of hockey due to a concussion sustained last March.

The 34-year-old's last game was a playoff game for the Bruins on May 6th against the Lightning.  He had been trying to make his return this season, but ultimately put his health and family first.
There were a lot of playoff teams checking in on Nash which means this obviously wasn't an easy decision.  At the end of the day, though, health comes first and Nash had a great hockey career and the hockey world congratulated him on it.
(H/T: Darren Dreger