Using your anecdote (and my own personal experience) I would venture a guess that pain and suffering can change a willing person more than any other kind of experience.

I spent a long time ignoring discomfort (pain-light) in my life. When I started nosing into the discomfort, the pain, and the hard things, I started to change. I had to be willing to do it, though, be willing to face that I was wrong, acknowledging that even the criticisms I had of myself were wrong.

I have changed more in the last year than I have over the rest of my life. The change has been huge.