It could be all sorts of things and it's probably cumulative, but as the old saying goes, when a man knows he is to be hanged in a fortnight, it clarifies the mind wonderfully. We all knew we would not live for ever, but there is a huge difference between that intellectual bit of knowledge and fearing you may have very little time at all. Which is the first reaction of most people to a cancer diagnosis. Even after treatment and lots more real information, we are seriously ill disposed to wasting our time. Or having other people wasting it for us. Or banging on about something trivial. Not only do we have to be kind to ourselves, we have to be kind to others who haven't had that rather nasty wake up call. Which is often difficult. Pat yourself on the back for the times you are patient and kind. And don't waste any more of your precious time worrying about when you just can't do it (again).