When you've been doing something
self destructive for some time (perhaps without realizing it) before
something serious happens that forces you to
come to terms with what you've been doing and that you need to stop.
Usually involves something medical but can involve anything serious.
He used to eat tons of
junk food, stuff with all sorts of sugar,
salty snack foods,
you name it. It doesn't help that he rarely exercised. He didn't seem to get that even the manufacturers of those foods stress the importance of a balanced diet. His wake up call was a heart attack that almost killed him. Fortunately, he took it seriously and made a lot of changes to his lifestyle.
They used to seem like they had everything. They lived well beyond their means. Most people thought they were rich. It took almost losing their house for them to start opening their eyes and living within their means. It was a real wake up call.