A few years ago I realized I'd been totally wrong for the past two decades - my entire professional life. It felt like my life had been wasted, because, in fact, it had been; none of the skills, none of the knowledge I possessed applied to my new situation. The solid steel building I thought I'd built was turned to sand and blown away in one terrible instant.
Now after years of previously unimaginable success following that epiphany, it all seems like a bad dream, like that part of my life really never happened. The current me is unable to see into the mind that made those mistakes. It was someone else. That guy could never have achieved what I have now.