Every Fool knows that playing the long-term investing game will have its ups and its downs. Human nature dictates that we are more optimistic during good times, and therefore more likely to purchase stocks. The same logic dictates that during rough stretches, we get pessimistic and are more likely to sell stocks.

Evolutionarily, this makes perfect sense. Alas, it will also wreak havoc on your retirement portfolio, as this forces you to buy high and sell low.

Fortunately for you, we Fools have gathered together 13 of our brightest Rising Stars and have them making real-money picks for you to follow absolutely free. These stars are aware of our tendencies to shy away during market downturns, and they've been showing their resolve in defeating this money-killing behavior.

Over the past 15 days, they have made nine different purchases of stocks. Below, I'll highlight five of those picks, and offer you access to a special free report at the end.

MAKO Surgical (Nasdaq: MAKO)
This company, which provides a robotic platform for doctors to use in knee and hip replacement procedures, was down 37% following a quarter which produced disappointing numbers and pessimistic procedure guidance for the future.

But that hasn't scared away Dave Meier and John Reeves. The team acknowledges the crushing blow dealt by the recent announcement, but thinks it's providing an opportunity to buy a long-term winner on the cheap.

Specifically, Dave sees two trends backing the company's focus on such procedures: an aging demographic that wants to remain active later in life, and rising obesity rates which put further strain on one's knees and hips.

Fusion-io (NYSE: FIO)
This company takes solid-state memory and uses proprietary software to help deliver data to server processors in an ultra-efficient manner. Dave Meier believes that the company's tools will become all the more important in the big data revolution we're currently in. He reels off several big name technology companies that are using Fusion-io's products in his video explaining the buy.

Fusion-io's customers are realizing that with the added efficiencies of data delivery, they are able to spend less money on actual servers. With the company's shares trading for about 20% cheaper than a few weeks ago, this team thinks the company is a buy.

Expeditors International of Washington (Nasdaq: EXPD)
Whew! That's a big name for a publicly traded company. Basically, this organization takes a bevy of intercontinental packages that need to be delivered, packages them all together to get lower transportation rates, then unbundles the packages to be delivered in the proper country. Rising Star Jim Mueller likes the company, and he's buying shares.

Jim is a big fan of the company's management and business model. By not actually owning and paying for the upkeep of an airplane fleet, Expeditors produces much better profit margins than the competition. Though concerns about global trade may hold volumes down for now, Jim believes that as the global economy cycles back into growth, this company will be a market leader.

Bridgepoint Education (NYSE: BPI)
Rising Star Jim Royal likes to focus on special situations, and he sees a golden opportunity in Bridgepoint. The for-profit-education sector has really taken a beating lately, especially in light of government regulation. That has led many schools to operate at a loss.

That isn't the case, however, for Bridgepoint. The company is estimated to make $2.54 per share this year, and the company is only trading for eight times that figure right now. With a share repurchase program in place to take roughly 7.5% of shares off the market, Jim sees a real possibility for a short squeeze in the coming weeks.

China Mobile (NYSE: CHL)
Finally, Rising Star Andrew Tonner sees a lot of reason to get excited about China Mobile. The company's home country has 980 million cell-phone users, but only 24 million smartphones were shipped in 2011. That means that there's a huge long-term opportunity for any company offering smartphones.

With the company rumored to be offering Apple's iPhone 5 when it comes out, Andrew thinks now's the time to jump on this company's bandwagon.

They're buying what?!?
Believe it or not, one of our Rising Star teams jumped into the Facebook melee and bought shares last week. It would be tough to find too many Fools who would agree with this move, but time will tell if it ends up being a smart contrarian play.

If Facebook isn't your taste, but you still want in on social media stocks, the Fool has prepared the perfect special free report for you: "Forget Facebook -- Here's the Tech IPO You Should Be Buying." Inside you'll find out all about a lesser-known play in the growing social sphere. Find out which company the report is referring to by getting a copy today, absolutely free!