It has been reviewed and reported over and over. Folks who thought they knew what they were doing in the stock market found out how wrong they could be about not only their investments but their ability to assume risks.
These folks were and many still are, advocates for investment choices. And many have postponed retirement, blaming not themselves and their unwavering belief that the markets would continue to rise but the markets themselves for not performing as expected.
For example, the CBS Marketwatch report suggests, without saying as much, that had you been in mutual funds and done nothing, you would be close to where you were at the end of 2007. But if you were in stocks you sold. And those losses will take a long time recovering.
Sticking with mutual funds that spread the risk over numerous sectors is still the best way to get where you are going. That and consistent, increasing contributions.