Image source: Ken Wilcox via Flickr.

Retirement planning requires discipline, and market turmoil tests everyone's ability to keep their calm. We're not even a month into 2016, and already it's shaping up to be one of the most challenging years ever for investors. Those who've gotten used to the stock market starting a new year on the right foot have gotten a slap in the face, as the Dow Jones Industrials (DJINDICES:^DJI) and the S&P 500 (SNPINDEX:^GSPC) have both been down by double-digit percentages in just a few weeks of trading. Yet despite that pressure, I'm optimistic that retirement investors will see the light and grab onto an opportunity they haven't had in a while. Let's take a closer look at some bold predictions for 2016.

1. Investors stuck on the sidelines will finally get into the market.
During the financial crisis in 2008, millions of investors panicked and took their money out of the stock market after suffering severe losses. At the time, many of them thought that stocks would continue to fall indefinitely, and so the shock of seeing the market recover so sharply in the years since has been a huge lost opportunity. As stocks have climbed to record levels time and time again, being on the sidelines has cost investors some huge returns.

Many investors have waited for what they saw as an inevitable pullback to get back into the market, and until now, stocks have been unusually stubborn in not giving them that opportunity. In late 2015, we finally had a 10% correction for the first time in several years, and some now expect the current pullback to take the Dow and S&P 500 to the brink of bear market territory.

The question is whether investors will finally jump on the opportunity when it presents itself. It takes a lot of courage to catch a falling knife in the stock market, but being able to buy stocks 15% to 20% more cheaply than they would have just a couple of months ago is powerful incentive. The smart way is not to try to time a reentry but rather to start slowly and ease in over time. You won't pick the perfect market-bottom that way, but you'll also get at least some of your money working for you if prices bounce back more quickly than anticipated.

2. Savings rates will rise.
Economic expansion has typically come with a drop in the savings rate in the U.S., because consumers drive growth by spending beyond their means in some cases. Yet since the financial crisis, personal debt levels have remained low, and the savings rate has remained at relatively high levels compared to what prevailed throughout much of the 2000s.

Data source: U.S. Bureau of Economic Analysis via St. Louis Fed.

Now, Americans are benefiting from lower energy prices that reduce how much they have to pay at the pump and for their heating bills, and that has led to an increase in discretionary income. Ordinarily, people might be more inclined to spend that newly found money, but with the stock market starting to fall, retirement investors are more likely to hold onto that spare cash and set it aside for longer-term needs. As you can see in the chart above, savings rate spikes aren't uncommon during recessionary periods, and if the current concerns blossom into a full recession, then we're quite likely to see savings rates rise even further.

3. Active managers will tout outperformance -- for the wrong reasons.
Actively managed mutual funds have underperformed passive index funds over the long run for a couple of important reasons. First, active management costs money, and added expenses make it harder for an active fund to match a cheaper passive fund. But another factor involves the fact that most active funds keep cash on hand, both to jump on cheap investment opportunities and to make it easier to handle potential outflows.

During up markets, having spare cash holds back performance, but it has historically led to less dramatic declines during major bear markets. If 2016 proves to be a big down year for stocks, you can expect active managers to outperform and to tout their acumen in avoiding the full extent of the losses in major indexes. But for most, the real reason will simply be that they held some of their money back on the sidelines -- something you can do just as easily yourself if you choose, without incurring higher fees in the process.

Planning for retirement is challenging enough without facing a tough market environment at the same time. Even with these challenges, I'm confident that retirement investors will be able to overcome them and find ways to make their retirement dreams come true.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.