I was having this conversation with someone yesterday.
I said, for me, it was like finally finding the courage to jump off a merry-go-round that is going too fast, even if I break every bone in the process, and, as I dizzily totter, throw up, and fall to the grass, saying, "God, I'll do anything not to have to clamber back up onto that merry-go-round again." And letting myself be led away.
He said, "it's when something snaps inside".
I'm going to go with his answer. Simple's best.