At times like this, it's hard to count on anything. Banks are still too big to fail, and although Ford (NYSE:F) earned a profit during the most recent quarter, GM is still losing huge amounts of money. People even think the recent rally is on its last legs.

But there are some good things we can count on in the investing world. For many people, that might be particularly good news, given what 2008 did to most of our investment accounts.

Good old history
For starters, we can count on history -- not as a guaranteed predictor of future events, but as a rather reliable guide of what to expect. We've suffered through market crashes before, and we'll likely do so again -- and after each one, the market has rebounded.

Before 2008, you were probably aware that the stock market had averaged gains of around 10% annually over many decades. After 2008, the average is ... almost 10% -- specifically, 9.6% between 1926 and 2008, according to Vanguard.

Focus on reality
When the stock market is having fits and investors are panicking, it can be easy to wring your hands, gnash your teeth, and think that the investing world as we knew it has come to an end, and that now, anything can happen. That seems kind of wrong to me. Sure, anything can happen in the short term -- as it quite emphatically did in 2008. But over the long haul, the market has pretty much always trended upward.

If you're a trader, you might think of shares of stock simply as electronic numbers that go up and down at random. But in fact, they represent a real share that you own in a real company. And just take a look at how some of those companies are faring:

Stock

TTM Revenue

Change From Previous Year

Best Buy (NYSE:BBY)

$47.3 billion

12.4%

General Dynamics (NYSE:GD)

$31.9 billion

10.3%

Amazon.com (NASDAQ:AMZN)

$21.7 billion

19.6%

XTOEnergy (NYSE:XTO)

$8.7 billion

18.5%

Celgene (NASDAQ:CELG)

$2.6 billion

25.3%

Priceline.com (NASDAQ:PCLN)

$2.2 billion

21.4%

Source: Capital IQ, a division of Standard and Poor's. TTM = trailing 12 months.

As you can see, even with the economy still struggling, these companies have seen their businesses hold up pretty well. People are still buying books and electronics. They're still traveling for the holidays, and they still need oil and gas. These are real companies, with real revenue and real earnings and real futures.

Sure, the recession has hit some companies harder than others. People are likely to put off buying big-ticket items if they can get away with it, so companies that rely solely on those items have suffered. Similarly, businesses may delay making big purchases, potentially hurting companies that cater to those businesses.

But America's economy isn't going away anytime soon. You can count on that.

Your brain, and time
You can also count on that grey matter in your head. That's one of the few things that can almost never be taken away from us. If you're stressing out about whether you'll have enough to retire on, you can put your brain to work by reading about your options, then taking action. You can start contributing to your IRA, or contribute more. ($5,000 invested per year and earning an annual average of 8% will amount to almost $250,000 in 20 years. Growing at 10%, it will top $300,000.) You can sock away more in your 401(k) -- and take steps to salvage it if you took a big hit last year.

How can I say any of that with any confidence? Because we can also count on time. Most of us still have plenty of time in which our investments can grow. Even if you're already 55 years old, you have a good chance of living another 30 years. If you're lucky enough to be in your 20s or 30s, you have enough time ahead of you to see the stock market work miracles. A one-time $10,000 investment that grows at 10% for 40 years, for example, will grow to more than $450,000!

So don't despair when times get tough. Remember that the stock market has always rebounded from its falls. Remember that it's based on actual tangible businesses. Remember that you have smarts and time on your side to make the most of it all.

When times are tough, you can't afford to make mistakes. Find out what John Rosevear says is the biggest mistake you'll ever make.