It’s never too late to start investing, and getting started in your late 30s can still set the stage for a good retirement. However, you’ll need plenty of financial discipline and the commitment to stick with it over the long haul.

Those were some of the key themes in the advice Reddit users shared with a 39-year-old who is just getting started with investing. The original poster wants to start small with $100 to $150 per week.

“For my own sanity, I want to invest in something that’s stable, but I wouldn’t mind a little risk as well,” the 39-year-old said.

Several Redditors offered their advice for getting into investing and making it work.

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Many Redditors suggested that the original poster open a retirement account and start contributing to it. Most suggested a Roth IRA since you don’t pay taxes on withdrawals or capital gains. Traditional IRAs make more sense for high earners who save a lot of money by deferring taxes.

Although anyone can open a traditional or Roth IRA and contribute their earnings to the account, it’s even better if you can contribute to an employer’s plan. 401(k) plans have higher annual contribution limits, which result in tax benefits for more of your assets.

“If your employer offers a 401(K) with matching, go with that,” one commenter said.

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The 39-year-old is just getting started and wants a stable investment that has some risk. That condition aligns with index funds, which mirror popular benchmarks like the S&P 500. This suggestion came up a lot in the comments,

“Start simple with the [Vanguard] S&P 500 ETF (NYSE: VOO),” one commenter said.

The S&P 500 is comprised of 500 of the largest U.S. corporations. There are several requirements for companies that want to join the index, such as profitability and a high market cap. The S&P 500 gets rid of underperformers each quarter and replaces them with promising corporations.

Index funds offer a hands-off investing experience. Some people build their wealth by setting up automatic investments that send some of every paycheck to a fund that tracks the S&P 500. The Nasdaq Composite is another benchmark to consider for investors who want to take on a little more risk and prefer more exposure to the tech sector.