Investors have a had a rough go of it lately. The ugly specter of the European debt crisis has returned once again, and investors (understandably) are not thrilled. After elections brought leftist (and in some cases anti-austerity) parties into power in France, but especially in Greece, it once again appears that a teetering Europe could snuff out what could be best characterized as a "fragile" global recover. It's these same fears that have had markets in a fit of late. The Dow Jones Industrial Average (INDEX: ^DJI) has meandered steadily downward since the beginning of May, shedding nearly 5%, while barely clinging to positive territory on the year. Other indexes have fared only slightly better. Both the Nasdaq and the S&P 500 returned 8.9% and 4.8%, although the recent malaise has knocked each index sitting well off its yearly highs. A recent rise in volatility also highlights the market's heightened tensions. Over the last month, the market's "fear gauge" or the VIX (INDEX: ^VIX) spiked sharply, gaining slightly more than 28.1%. Given all this uncertainty, what's an investor to do?

Fool me once...
It's moments like these where investors need to circle their proverbial wagons. For the investor with an extended time horizon, a falling market can actually be a good thing. Last year, when the global debt crisis reached its crescendo, I shied away from getting scooping up companies I loved for fear of things getting worse. Apple (Nasdaq: AAPL) and Google (Nasdaq: GOOG), companies I both cover and love as a stocks, sold at what I believed was a bottom-barrel valuation (not that it required any particular insight). Had I trusted the strength of my convictions, especially as a young investor with a very long-term horizon), I'd have pocketed some outstanding returns. Instead, I pulled a Chicken Little and let a great opportunity pass by me.

Won't get fooled again
My lesson in personal stupidity does circle us back to a sensible way forward for most investors. As things get cheaper, focus on finding stocks that you're comfortable owning for a long time (think 10-plus years). One company in my crosshairs is fast-food blue chip McDonald's (NYSE: MCD). With its virtually unbreakable business model (it succeeds in weak and strong economic conditions) and amazing history of generating returns for investors, I'm watching the golden arches like a hawk. While I still find it a little expensive. However, it's the kind of stock I'd be glad to slowly build a position in, and my cost basis only gets more favorable the cheaper it gets. Stocks like McDonald's show all the signs of being long-term winners, the kind of stocks that fund your retirement. 

The Fool also thinks it's identified three more stocks that share these kinds of winning characteristics. We detail them in our retirement-focused research report, which you can grab a copy of by just clicking here.

Remember, as with any risky activity (of which investing certainly is one), you'll never see an opportunity perfectly until it's passed you by.