The market has rallied over 25% since last October. The S&P 500, Dow Jones Industrial Average, and Nasdaq composite have been trading around new 52-week highs.

In theory, this means we’ve entered a new bull market. However, many people simply don’t care about or accept that. Last year’s scars are still fresh.

Many institutional investors—mutual funds, foundations, retirement plans—remain hesitant about the market’s prospects and aren’t participating. According to the June Marquee QuickPoll, which surveyed nearly 900 institutional investors, only 3% of these investors classify themselves as “bullish.”

JPMorgan recently asked these investors if they plan to increase or decrease exposure to stocks in the near future. Cash remains their largest position. They’re most bearish on stocks, with only 17% of them looking to add to stock exposure.

It’s when they all plan to add to stocks that you should start to worry.

Currently, it’s the exact opposite; they’re all scared to death.

Sentiment in the market is always among the most influential factors over the short-to-medium term—meaning weeks to months—as emotion swings with headlines, economic reports, and the latest corporate news.

Even if the day-to-day circumstances change, markets generally don’t. As Ben Graham, Warren Buffet’s mentor, so aptly described, the markets will still be voting machines in the short term, registering the world’s feelings. And in the long run, they’ll still be weighing machines, registering likely corporate earnings over the next three to 30 months.

Remember, after the greatest first half to the Nasdaq in history, most of these same Wall Street strategists currently retain their most bearish second-half outlook on record. Who are all these people listening to or talking with? Each other, it would seem.

When it comes to investing, this means you have a choice.

You can respond to the financial media, following their endless cycles of “buy, buy, sell, sell,” making yourself miserable while dealing with all the emotions that come with that. Or you can get rewarded for ignoring the daily noise. You, instead, focus on what matters when it comes to successful investing. And that’s time. Not as in quarter to quarter, but as in multiple years.

If you invest and the market goes down 20%, you may regret that for a matter of months. If the market runs away from you, and you freeze, you’ll end up regretting it for the rest of your life. By far, the most powerful emotion in investing is long-term regret.

There’s no single way to invest that will guarantee success or the results you would like. That’s why diversification and asset allocation are so important—much more so than which specific investments you have.

There is one sure way to guarantee terrible results with your life savings: Don’t invest your money. If you just keep your savings in the bank savings account, a money market fund, certificates of deposit, or even bury it in your backyard, you surely won’t have to worry about all of the risks that are a key part of the stock market.

You’ll also totally crush any chance of increasing your wealth over time.

Investing in stocks is risky, which is why the returns are relatively high. Valuation methods may tell you something about long-term returns. Most tell you almost nothing about where prices are headed over the next 12 months.

In the short term, the opportunity cost—the loss of potential gain from other alternatives—of sitting in cash is very little. On average, cash only underperforms the stock market by 8% over one-year periods. But the differential increases exponentially over time.

Over a five-year period, the difference in return between stocks and cash is more than 50% in favor of stocks. Over 20 years, it’s more than 700%.

The lesson is clear: The opportunity cost of keeping large amounts of assets in cash is huge and grows over time.

Only two years ago, three-month Treasuries were yielding nothing. That environment changed in a hurry. Currently, using three-month Treasuries as a cash proxy, you can earn more than 5%. This is the highest yield since 1995.

Stating the obvious, it feels comfortable to earn 5% while having just a fraction of the price risk of stock. However, being comfortable likely isn’t going to take you where you want to go. There’s no one special approach, no perfect allocations, or times to invest in stock. The answer is only obvious with the benefit of hindsight. The best thing you can do is figure out an allocation now that works to get—or keep—you where you want to be.

While holding cash may make you feel good in the short term, the long-term track record of that decision could have a major negative impact on your retirement goals.

You likely will have short-term cash needs—saving for a house, tuition payments, and so on—and that money should not be in the market. My feeling is that if you double-sure need a chunk of money for a specific purpose within three years, you must have it in some fixed-income or money market investment to be sure it’s there for you. This is a good environment for those types of situations. But, for goals with longer time horizons, despite our relatively higher rates, cash should not be thought of as a stock substitute.

None of us can control what happens in the markets. Focus on what you can control, such as attitude and contributions, and let the market do what it will.

Your best approach is to save, invest, and follow your strategy, no matter what the market is doing.