Think back a year ago, when politicians in Washington were in the grip of one of their now-familiar “fiscal cliff” standoffs. As has become customary, the theater of brinksmanship kept everyone guessing until a last-minute resolution was reached.

“The Economist” magazine’s tone about 2013’s prospects was skeptical.

“Although investors are not as complacent as they were heading into 2000 or 2007, say, it is still hard to believe this will be a bumper year for returns,” said Buttonwood’s Jan. 5, 2013 column.

It’s easy to see from this example that many investors might have taken fright at the developments around the turn of the year and sought to trim their exposures to risky assets because of what media pundits were saying.

That would have been a shame because, as of early December 2013, many global equity markets were notching record-breaking years. As the year ended, plenty of gloomy stories still filled the newspapers — including some about ongoing speculation on what happens when the U.S. Federal Reserve begins tapering its monetary stimulus program.

This isn’t to say these stories are necessarily incorrect. Most of them accurately reflect the sentiment prevailing at the time they were written and the uncertainty about the future. But you can do little about that as an individual investor.

Investing is about what happens next. We don’t know what happens next, which is why we diversify.

Anyone who says he can tell you what is going to happen next is lying to you.

Making drastic allocation changes to a portfolio after the fact is akin to slamming the stable door after the horse has left. Bottom line: Are you looking through the windshield of opportunity or the rearview mirror of past performance?

And think about this: If any of the gurus who regularly appear on financial TV or in the newspaper really had a crystal-clear view of the future, why would he bother sharing it with the world?

It makes more sense to focus on what’s within your own control.