This is probably one of the best advises that I have ever read:

From Business Week Oct 6, 2008:

Richard Thaler, 63, professor of behavioral science and economics, University of Chicago Graduate School of Business (when he was asked where he puts his money):

I have not looked at any of my holdings and don’t intend to. I don’t want to be tempted to jump because I think I’d be more likely to jump in the wrong direction than the right one. My advice has always been to choose a sensible diversified portfolio and stop reading the financial pages. I recommend the sports section.