(Washington Post illustration)

When you’re young, you tend to think you have more than enough time.

Then the time comes to do what you put off, and you realize time has gotten away from you.

The one mistake many millennials are making is not taking advantage of the stock market by investing while they are young — when their money has time to grow.

Fearing the market, millennials are putting their money in savings accounts. And the potential loss of future earnings is huge, like $3.3 million huge, according to new analysis by NerdWallet.

The online site says it looked at 40 years of market returns and interest rates. Using that data, they factored in how much a 25-year-old earning $40,456 saving 15 percent of this income could amass, assuming the market does what it’s done.

“To capture the wide range of possible outcomes, we ran thousands of simulations based on historical returns and volatility,” wrote Arielle O’Shea and Stephane Lesaffre. “For simplicity, this analysis focuses on a portfolio 100 percent invested in the market, but that allocation may be too aggressive for some millennial investors.”

What did they find?
— Over the 40-year period, an investor could potentially have (past performance doesn’t guarantee future returns) $4.57 million before adjusting for inflation and fees.

— You can save $1 million, but you could accumulate so much more by investing.

— The mattress will get you to only $563,436 over a 40-year period.

It is understandable young adults are scared of the stock market. Heck, older folks are, too.

“Millennials came of age during the 2007-08 financial crisis, either investing for the first time during it or watching parents suffer the fallout,” O’Shea and Lesaffre write. “But context is key: Our 40-year analysis includes the Great Recession — the market ended 2008 down 37 percent — as well as the dot-com bubble burst and several other years of significant losses. Still, the S&P 500 had an average annual return of 10.96 percent during the 40-year period analyzed, before inflation.”

Old or young, read NerdWallet’s analysis. It makes a great case for not being afraid to invest over time.

Color of Money question of the week
Do you wish you had started investing sooner? Send your comments to colorofmoney@washpost.com. Please include your name, city and state. Put “Stock Market” in the subject line.

Live chat today
Think ahead. It’s 2029, and the president says the United States will default on its loans.

Overnight your retirement savings is wiped out. Mexico built a fence to keep out poverty-stricken Americans.

Could you survive such a crisis — by any means necessary?

Let’s talk about what you would do if faced with an economic meltdown in the United States. That’s the premise of the Color of Money Book Club pick for this month, “The Mandibles: A Family, 2029-2047,” by Lionel Shriver.

Shriver will be joining me to discuss her book.

Here’s my review of her book: “A horror story: What would you do if the U.S. economy collapsed?”

Join me to talk about Shriver’s novel and any other personal finance question you might have.

Instead of ‘1984,’ read this

To participate in the discussion, click this link.

Taking sick leave for a mental health day. And your boss doesn’t bash you for it.

A lot of people are still talking about an employee who was honest with her boss about using sick leave for mental health reasons.

The mental health email shared ’round the world

The woman’s boss responded with this email: “I just wanted to personally thank you for sending emails like this. Every time you do, I use it as a reminder of the importance of using sick days for mental health — I can’t believe this is not standard practice at all organizations. You are an example to us all, and help cut through the stigma so we can bring our whole selves to work.”

Last week I asked: What are your thoughts on taking sick leave for mental health issues?

The one comment that stood out for me came from Earl Roethke of Minneapolis, who wrote, “I enjoyed your article discussing the quaint practice of sick leave. Before I was laid off in May, my company, like many others, had dispensed with this practice. If you’re sick, you use your personal time off, aka, vacation. It eliminates the need to hide anything. It also means that people come to work when they’re physically sick.”

I’d like to hear from people in a similar situation. Do you work for a company that officially or unofficially discourages workers to take time off? Send your comments to colorofmoney@washpost.com.

Here’s something to note: More states adopt tough paid sick-leave laws

Arizona recently became the seventh state, plus the District of Columbia, to adopt a sick-leave measure, reported Russ Wiles for USA Today.

Color of Money columns this week
Knowledge isn’t power. The right knowledge is power.

Stay informed about your money. Read and share some recent column.

Is there a freeloader living in your home? Set some ground rules.

The CFPB rule on class-action suits is a win for all — even if it doesn’t seem like it

Have a question about your finances? Michelle Singletary has a weekly live chat every Thursday at noon where she discusses financial dilemmas with readers. You can also write to Michelle directly by sending an email to colorofmoney@washpost.com. Personal responses may not be possible, and comments or questions may be used in a future column, with the writer’s name, unless otherwise requested. To read more Color of Money columns, go here.