Most investors don’t worry about costs. After all, isn’t it the returns that are the most important part about investing? Investors want high returns, and as long as the returns are in an acceptable range, fees don’t seem to matter.

During the last several years, we’ve experienced exceptional stock market advances. Last year’s Standard & Poor’s 500 index returns clocked in at 13.48 percent, and 2013 more than doubled that with a stratospheric return of 31.15 percent. If you look back at 2012, the market returned 15.89 percent, and 2012 took a breath with a 2.10 percent increase after 14.82 percent and 25.94 percent returns for 2010 and 2009, respectively.

Those remarkably high stock market returns make investors both giddy and complacent. Realize that when stock market returns are above the long-term average of 9.6 percent (1928-2014), there’s a statistical tendency to revert to the mean. In other words, there’s a strong likelihood that returns are going to head back to normal.

You may not think much about fees now, but imagine how you may feel with 1 percent or 2 percent stock market returns, or even worse, negative returns and fees zapping up to 1 percent or 2 percent of your total assets.

Investment fees matter. Let’s look at a few scenarios to understand the effect of high fees on a typical investment portfolio.

JoAnn is 40 years old and has an investment portfolio worth $200,000. She expects to retire at age 66. For the sake of this example, assume she doesn’t put any more money into her account (not a great idea). JoAnn doesn’t worry about fees and has actively managed mutual funds, and part of her money is with an investment advisor. Her average fees as a percent of total assets are 1.75 percent.

That means every year she’s paying out $3,500 in investment management and oversight fees. Multiply that $3,500 by 26 years until retirement, and at age 66, she’ll have shelled out $91,000 in fees. During the years her portfolio earns less than a 1.75 percent return, she’ll earn nothing on her investments.

Daren is also 40 years old and much smarter about investing than JoAnn. He invests in low-cost index and exchange-traded funds. He also has a portion of his portfolio with an advisor — a low-fee robo advisor — who also invests in low-cost index funds.

Daren also has a $200,000 investment portfolio, but his fees average 0.30 percent of his total assets. Unlike JoAnn, who pays $3,500 per year in fees, Daren pays just $600 per year on his investment portfolio. That’s $2,900 per year less than JoAnn. Over 26 years, when Daren retires at age 66, he will have paid just $15,600 in investment fees.

JoAnn paid almost six times more than Daren during their future investing horizon.

Do I have your attention?

How to create a low-cost investment portfolio. It’s easier than you may think. Let’s take a look at some typical mutual funds and ETFs and their fees. This is not a recommendation to buy or sell any investments, nor is this advice on constructing a portfolio.

These are sample, diversified low-fee stock and bond index funds, along with their fees listed as a percent of total assets invested:

When creating your investment portfolio, be mindful of fees. The money paid out in management fees doesn’t guarantee higher returns and detracts from your overall opportunity to build long-term wealth.

The best way to create a low-fee investment portfolio is to pay attention and choose low-cost index and ETF funds. Don’t let careless investment oversight cost you thousands of dollars. Before investing in any mutual fund, look at the fee structure. And, if you work with an advisor, ask him or her what the fees are on the funds in your portfolio. If they’re too high, then ask for lower-fee replacements. Fees matter!

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How to Create Your Lowest-Cost Investment Portfolio originally appeared on usnews.com