In just 16 days, we'll officially be ushering in a new year and a new decade. That means for tens of millions of Americans, it's once again resolution time.

For most Americans, New Year's resolutions are often health-related, such as wanting to lose a few pounds, exercise more often, or quit smoking. But there's an even more important resolution that most Americans should be making in 2020: to take control of their own financial destinies.

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Money managers aren't doing you any favors

I get it -- it's really easy to invest your money in mutual funds and allow the fund managers to do all the hard work when it comes to growing your money over the long run. But fund managers aren't really that good at their jobs if you really dig into the data.

Every year, S&P Dow Jones Indices is responsible for releasing the SPIVA U.S. Scorecard, a report that examines the performance of fund managers to their most closely linked benchmark index. Rather than trying to compare every single fund to the performance of the broad-based S&P 500 (SNPINDEX: ^GSPC), the SPIVA U.S. Scorecard takes a number of factors into account to provide a true apples-to-apples comparison of how money managers are doing relative to the broader market.

In 2018, the report showed that nearly 69% of domestic equity funds underperformed their benchmark index. But things get much worse if we look out a bit further. Of the 17 major U.S. equity fund categories in the SPIVA report, 88% underperformed their benchmarks over a five-year period, 84% over a 10-year period, and a whopping 89% over a 15-year period. These money managers may have created wealth for their clients, but if you had simply bought an index fund, your portfolio would have made more money almost 9 out of 10 times compared to putting your money in mutual funds.

How can fund managers who invest other people's money for a living be so bad at their jobs? For one thing, too many fund managers are focused on the short term and ignore the wealth creation that comes with holding an investment for long periods of time. Another problem is that most money managers are too focused on being liked by the companies they own a stake in or cover and fail to look at the risks associated with an investment. Additionally, but perhaps most importantly, there's rarely any accountability. Fund managers are going to get paid no matter how well or poorly your money performs.

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It's time to take control of your own financial destiny

All of these factors summarize why it's so important that you take control of your own financial destiny in 2020.

The best part is that you don't need to be a financially savvy money manager to build wealth over the long run. Here are two tricks that could allow you to generate fund-manager-topping returns in 2020, even if you've never invested in the stock market on your own before.

Buy an index fund or targeted fund

Investing doesn't have to be complicated. If you don't feel comfortable analyzing individual companies or don't have the time to devote to doing so, consider buying an index fund or a targeted fund.

An index fund, as the name implies, closely mirrors the performance of a specific index, less money management fees (i.e., the fund's expense ratio). For example, the SPDR S&P 500 ETF (NYSEMKT: SPY) is designed to closely mirror the performance of the broad-based S&P 500. It won't perfectly match, given the negligible annual net expense ratio of 0.09%, but it'll be pretty darn close.

With the SPDR S&P 500 ETF, you'll gain access to the roughly 500 companies that the market-cap-weighted S&P 500 takes into account when calculating the point value of the index. That means instant diversification with a single click.

Furthermore, the S&P 500 has a history of expansion on its side. Despite there being 37 stock market corrections of at least 10% (not including rounding) in the S&P 500 since the beginning of 1950, each and every one of these corrections was eventually followed by a bull-market rally. Often, it takes just weeks or months to put pessimism in its place. While there are few certainties when it comes to investing, 37 out of 37 is about as close to a stock market guarantee as you'll get.

If an index fund sounds a bit too "boring," consider a targeted fund. There are well over 1,700 ETFs in the U.S. to choose from, allowing investors to target specific investment variables, such as market cap, value or growth, domestic or international investment, or even certain industries, such as technology or biotech. The choice is entirely up to you.

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Focus your research on what you know and what interests you

On the other hand, if you would prefer to own individual stocks, you certainly don't need to dig too far into the weeds to find great companies. By focusing on companies within the industry you work or within industries or sectors that interest you, you'll often come away with a handful of intriguing investment ideas.

To throw out an example, pretty much everyone is familiar with Amazon (NASDAQ: AMZN), the e-commerce giant that'll be responsible for nearly 40% of all online shopping in the U.S. in 2019 and roughly 5% of all retail shopping in the United States. Amazon's retail-landscape dominance, along with its Prime membership, helps keep consumers within its ecosystem of products.

But dig a bit deeper into one of consumers' favorite companies and you'll also discover that Amazon is a giant in the cloud-servicing business. Amazon Web Services (AWS) is growing at a much faster pace than the company's traditional e-commerce operations, and more importantly, is a much higher-margin segment.

For instance, Amazon's e-commerce segment has generated a little over $4 billion in operating income on $168 billion in sales through the first nine months of 2019. Comparatively, AWS has produced $6.6 billion in operating income on $25.1 billion in sales over the same time frame.

Here's the point: Great companies are all around us. You simply have to be willing to dig in a bit to see what really makes them tick, and then determine if they're a good fit for your long-term investment portfolio.

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John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Sean Williams has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Amazon. The Motley Fool has a disclosure policy.