Are you looking to build a worry-free, passive long-term portfolio that will allow you to focus on other things while growing your money? Buying and holding a handful of exchange-traded funds (or ETFs) is the answer, of course, and the SPDR S&P 500 ETF Trust (SPY 0.65%) remains a top choice.

If you're truly looking for lifetime holdings though, you may want to consider a slightly different solution that allows you to adjust your overall allocation as time marches on. Namely, you'll want to buy a handful of different (but complementary) ETFs that can be individually scaled back or added to as your risk tolerances change.

If you have $1,000 in cash available to invest that isn't needed for monthly bills, to pay off short-term debt, or to bolster an emergency fund, here's a combination of ETFs to consider that will likely set most investors up for a lifetime of strong performance.

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Vanguard Growth ETF

If this really is going to be a "forever" portfolio, it's a reasonably safe bet that growth is a priority for most of the time frame in question. The Vanguard Growth ETF (VUG 0.50%) will handle this part of the overall job nicely.

Just as the name suggests, the Vanguard Growth ETF holds a basket of growth stocks. The fund currently holds significant stakes in Apple, Microsoft, and Nvidia ... some of the market's top-performing growth names of late. Although this company weighting evolves over time as some companies' market caps outgrow others, this ETF gives you a great shot at major long-term capital gains.

VUG Chart

Data by YCharts.

There's a very particular reason, however, you might want to own the Vanguard Growth ETF instead of seemingly similar alternatives like the Invesco QQQ Trust, which holds many of the same stocks. That's the fact that this fund is meant to mirror the CRSP U.S. Large Cap Growth Index. (CRSP stands for the Center for Research in Security Prices.)

That won't mean much to most people. This might get your attention though: The CRSP Large Cap Growth Index largely sidesteps the common problem of taking on too much exposure to the market's very biggest companies, which in turn leaves investors vulnerable to sizable setbacks once the tide finally turns against these top names.

That hardly makes it an "equal weight" index, to be clear -- it's still measurably top-heavy.

The fund is top-heavy to a degree that's tolerable and even a little desirable, however, by virtue of ensuring a little bit of overexposure to companies that are becoming much bigger due to actual top- and bottom-line growth.

Schwab U.S. Dividend Equity ETF

Growth stocks aren't the only way for your portfolio to achieve net growth, of course. It can also be done by a slow and steady (and ever-rising) flow of fresh cash into the account, which is then used to purchase more of whatever's generating that income. For some investors, that will be bonds and other fixed-income instruments. For most people though, this income will come from dividend-paying stocks.

The irony? High-quality dividend-paying stocks often end up outgaining the broad market anyway.

Mutual fund company Hartford crunched the numbers, determining that since 1973, stocks of companies that were able and willing to consistently grow their dividend payments produced average annual net gains of more than 10% (assuming reinvestment of those dividends) while stocks that didn't dish out any dividends didn't perform half as well. Moreover, reliable dividend payers were the market's least volatile stocks during this stretch, making them easier to stick with during turbulent times.

SCHD Chart

Data by YCharts.

What gives? The best explanation is the argument that quality always eventually shines through, and a reliably growing dividend is a good sign that a company is solid and well-run. Although there's certainly the occasional exception to this norm -- think non-dividend-paying Nvidia -- identifying these exceptions isn't always easy. You should invest based on your best odds, particularly when you're thinking in terms of a lifetime.

The Schwab U.S. Dividend Equity ETF (SCHD 0.61%) is arguably the best way to plug into this dividend-driven dynamic. Based on the Dow Jones U.S. Dividend 100™ Index, this ETF doesn't simply hold what appear to be the market's most promising dividend stocks. In addition to requiring at least 10 consecutive years of annual dividend increases, inclusion in this index also considers fundamental factors like free cash flow versus debt, return on equity, and its typical dividend growth rate. Each prospective constituent is then ranked on these metrics to screen out all tickers other than the best 100 names.

While this approach seems quite mechanical, that's the reason it works so well. There's no misleading emotion, presumption, or bias built into the selection and rebalancing process.

iShares U.S. Technology ETF

Finally, add the iShares U.S. Technology ETF (IYW 0.17%) to your list of ETFs to buy and hold for a lifetime if you've got $1,000 -- or any other amount of money -- you'd like to put to work for a while.

It's obviously different than either of the other two exchange-traded funds suggested here, both of which represent a unique investing school of thought. A sector-based fund is more strategically precise, calling into question whether or not it's actually capable of being a true lifetime holding. And maybe it isn't. It would be shocking, however, if the technology sector wasn't a great one to plan on holding for the long haul, even if you can't fully see its future.

IYW Chart

Data by YCharts.

Think about it. Ever since personal computers began proliferating back in the late 1990s, the world has increasingly become digitized. Automobiles have them on board, and people would struggle to function without the mini mobile computer they now carry around in their pocket or purse. Artificial intelligence is now being used by the pharmaceutical industry to discover, design, and digitally test new drugs. Factories are made more efficient by being able to instantly share and create actionable data. At the heart of all of it is technology, and now that we've seen what it can do, we're certainly not going back to the "old way" that was less efficient and less effective. Now, one of the world's most commonly asked questions is: How can we use technology to make things even better?

There's more than one exchange-traded fund that would fit this bill, but the iShares U.S. Technology ETF is arguably the best all-around prospect thanks to how it weights its holdings.

Built to mirror the performance of the Russell 1000 Technology RIC 22.5/45 Capped Index, this fund -- like the aforementioned Vanguard Growth ETF -- at least attempts to maintain a reasonably balanced allocation even when the market itself is becoming top-heavy thanks to the ongoing growth of a small handful of massive companies. As Russell explains in a factsheet on the index, "At the quarterly index reviews, all companies that have a weight greater than 4.5% in aggregate are no more than 45% of the index, and no individual company in the index has a weight greater than 22.5% of the index."

This approach doesn't always perfectly accomplish its goal. Right now, for instance, Microsoft, Nvidia, and Apple collectively account for about 45% of the index's value. That's not particularly well balanced.

The weighting rules will help more often than not in the long run though, and will certainly help more often than they hurt.