Most people don't have them, and you should thank God for that.
As one who had a couple, a very long time ago, I can tell you that there is frequently no proximate cause, though stress is often cited as tributary. There is no warning, and there are no lingering effects, unless you incur some secondary injury during the seizure.
Those I had came on me in my sleep. I awoke with a complete inability to control my own body; a very wierd predicament, indeed. I could hear myself, and I could hear everyone else in the room, but I had exactly ZERO control; I couldn't even open my own eyes. Throughout each event it was is if I were merely an inside observer, powerless to intervene.
and as long as we are praying, let’s ask God for even greater mercy by helping one of the really older justices to retire (Souter, GInsberg, Breyer)...This year!