While 10- to 15-year lows are not common, they do happen. During these times, don't be shy about going against the trend and investing; you could make a fortune by making a bold move or lose your shirt. Remember the first quote in this article and invest in an industry you've researched thoroughly. Then, be prepared to see your investment sink lower before it turns around and starts to pay off.
"I will tell you how to become rich. Close the doors. Be fearful when others are greedy. Be greedy when others are fearful." — Warren Buffett
Be prepared to invest in a down market and to "get out" in a soaring market, as per the philosophy of Warren Buffett.