I think the 2003 motorcycle accident was a major turning point. I feel like we had two different MKs before and after like after 9/11 we had two different worlds. When you realize you're just a human and can die at any point, no matter how much money and fame you've got, that's refreshing.
But, with that said, almost any major 'accident' in life is a turning point, whether it's the death of a relative, a divorce, a wedding, it's all turning points.