As the years go by, people tend to forget what it was like to be a carefree youth with next to no responsibilities and your entire future ahead of you. The drains of the real world can be, well, draining.
Even for current and former professional athletes.
So many athletes who started their careers as bright-eyed optimists with a smile permanently glued to their face have gradually descended into a darker place, and all of them have their own reasons.
That's assuming they were ever affable and inviting human beings to begin with—and many were not. Some people are just born with the personality and sensibilities of The Simpsons' Mr. Burns.
Getting old and cranky can manifest itself in various ways. It could be something as harmless as taking the filter off and speaking your mind about someone you never would have dared to mention as a young man.
Or it could be something as serious as developing a God complex, which has the potential to make you a danger to everyone around you. Or just make you extremely irritating.
Here are 20 athletes who want you to get the heck off their lawn.