This is ultimately true. And, in many circumstances, very good advice to follow. But, with all of that, the saying is still in many cases misleading.

Example: your dad gets diagnosed with Alzheimer's dementia. He's 70 and his body is physically in good shape. Yeah, the situation changed. He died. But, I also went through 12 years of Goddamn absolute fucking hell on earth, so, you know...these sayings only go so far.