My wife had one in 2011 as a result of a vertebral artery dissection after running a triathlon. It was very painful, and destroyed almost 1/4 of her cerebellum. She was 37 at the time, and in amazing shape.
She's recovered fully. As a matter of fact, she ran two triathlons this past summer, the Boston Marathon this past spring, and the NY Marathon this past weekend.
In short, age and health doesn't matter. It can happen for any number of reasons. And you can recover fully depending on the severity. The brain has redundancy built in. It still sucks, though. This isn't a toothache, and people shouldn't joke about it.