The TV game show Who Wants to Be a Millionaire? was always fun to watch, in my opinion. However, there was one big problem with it: Too few contestants actually became millionaires. In nearly 400 episodes spanning 22 seasons of the U.S. version of the show, only 14 people walked away with at least $1 million.

You might think the odds of retiring as a millionaire are daunting, too. But they don't have to be. Here's how to build a millionaire retirement while barely lifting a finger. 

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Three key ingredients

You don't have to be an expert investor to retire with $1 million or more. However, you will need three key ingredients.

First -- and most importantly -- you'll need the discipline to save regularly for retirement. Ideally, you will sock away money every month in a tax-advantaged retirement account such as an IRA or Roth IRA

The second ingredient is time. The sooner you begin saving for retirement on a regular basis, the more likely it will be that you'll reach the $1 million goal by the time you retire. 

Don't fret if you didn't start as early as you could have, though. It just means that you could need to increase your investment amounts and/or push back your retirement somewhat to build up $1 million.

What's the third key ingredient? Smart investment options that give you an excellent chance to reach your retirement goal.

Two great ideas

I can't help you with the first two ingredients for building a millionaire retirement. However, I will share what I believe are two great ideas for the third one.

Warren Buffett stipulated in his will that the money that his family will one day inherit from him should be invested primarily in low-cost S&P 500 index funds. He suggested Vanguard funds. I think that Buffett's recommendation is one for anyone to seriously consider.

The Vanguard S&P 500 Index Fund ETF (VOO 0.92%) attempts to track the performance of the S&P 500, which consists of the 500 largest U.S. companies. Over the long term, the S&P 500 has delivered solid returns. And the Vanguard S&P 500 Index Fund ETF is a cost-effective way to invest in the S&P 500 with an expense ratio of only 0.03%.

While the S&P 500 has performed well over the long run, small-cap stocks have delivered even better returns. Small-cap value stocks especially stand out. These stocks have generated stronger earnings growth and greater returns than any other asset class going back to 1936, based on an analysis conducted by Wellington Management. 

Fortunately, there's an easy way to invest in small-cap value stocks. You can buy the Vanguard Small-Cap Value Index Fund ETF (VBR 1.10%). This exchange-traded fund owns more than 870 stocks with relatively small market caps and valuations that are more attractive than the overall market. Its expense ratio is a low 0.07%. 

The nice thing is that you can automate your monthly investments in either of these ETFs. Once you've set this up with your brokerage, you won't have to do anything else.

A realistic scenario 

How can you retire with at least $1 million? Let's assume that you're 30 years old and plan to retire at age 67. You regularly invest $350 at the beginning of each month in the Vanguard S&P 500 Index Fund ETF held in a Roth IRA. (Choosing this approach means that you won't pay taxes on any accumulated gains.)

The S&P 500 in its current form has generated a historical average annual return, adjusted for inflation, of around 8.5%. Let's assume you achieve this same return. When you retire at age 67, your retirement account will have grown to nearly $1.1 million. 

What if you invested $500 per month? You'd retire with over $1.56 million.

Walk away as a winner

Unfortunately, there's no ironclad guarantee that you'll be able to obtain the same return as the S&P 500 has historically delivered. On the other hand, it's possible that you could make even better returns. Investing in small-cap value stocks could potentially increase your chances of doing so based on their historical performance.

Regardless, though, you could walk away from the working world one day as a winner. Exercise the discipline to invest for retirement regularly. Start saving as early as possible. Invest in low-cost index funds.

Who can be a millionaire? The correct answer just might be "you."