Calvin Johnson still seemed to have plenty of good years left when he retired in 2016. Stephen Brashear/Getty
- Andrew Luck surprised the NFL world by retiring at 29 years old.
- Throughout sports history, there have been professional athletes who have retired earlier than expected, often times because of injuries.
- Check out some examples of athletes who have called it quits relatively early.
- Visit Business Insider's homepage for more stories.
Andrew Luck's decision to retire caught the NFL world by surprise, but he's hardly the first athlete to call it quits early.
In fact, Rob Gronkowski decided to retire at the same age as Luck, just a few months beforehand. More NFL players may follow their lead.
Throughout sports history, there have been surprising retirement announcements from players who figured to have plenty of years left in their career. Most of the time, injuries play a big part in their decision to hang up their jerseys.
Here are a few examples of professional athletes who ended their careers earlier than expected.