Bret Hart recently spoke with Sports Illustrated about a number of topics including the health of Daniel Bryan and his current situation which he likens to his career ending injury:

“Daniel Bryan is finished. He’ll never wrestle again. I don’t think he knows it yet. I feel terrible about Daniel Bryan. For all intents and purposes, he had the exact same thing happen to him that happened to me after Bill Goldberg kicked me in the head [ending Hart’s career]. One day, you learn it’s over. Doctors tell you that you can’t wrestle and you’ll never wrestle again. I lost millions of dollars because of that. I pray that it’s not the same for Daniel Bryan.” Click Here to read the full interview.

This is the kick that ended Bret Hart's career. After receiving this botched kick (it being the initial concussion), Hart suffered a chain of concussions during the course of this match that caused him to have post-concussion syndrome. Though he was not immediately aware of how severe the concussion was, he retired five matches later after learning of his situation. It happened at Starrcade 1999.