Old buddy of mine, ex-Air Force and retired as a Check Airman on the 757, went back into what he thought would be a fun and relaxing way to occupy his time at a large airline training school. He was working ridiculously long hours without proper or planned breaks, teaching unmotivated students in plastic trainers that didn't perform well in the environment they were operating but he carried on, never losing his enthusiasm to pass on his knowledge and skills until the day he didn't come back and he, his student and another CFI that was with them that day were found three days later in the burnt out wreckage of their airplane following an impact with a canyon wall. Never got to enjoy his retirement.