In 1997, HBK was supposed to wrestle Bret Hart in the main event of WrestleMania 13 and drop the belt to Hart in a rematch to their WrestleMania 12 match where HBK won the title.
HBK and Bret Hart didn't get along and he didn't want to do the job so a month before Mania, he came on RAW with a doctor's note and said that his knee is injured and that he has to retire and that's when he said that he lost his smile and will go back home to find it
He then returned full time to wrestling a couple of weeks after WrestleMania 13, miraculously fully healed.
Via their ranking in the Nations league