
Nothing! Yes that's what you should do ....NOTHING..... just wait it out. Do you have any other choice?
It's common sense, how can markets go up forever? Unless you want to cut lost, when it's down you just need to be patient, go for a trip, learn something new , read some books or whatever that works for you. And of course stop complaining. It is not going to help & makes everyone including your self feel worst!