As millennials begin to turn 40 in 2021, CNBC Make It has launched Middle-Aged Millennials, a series exploring how the oldest members of this generation have grown into adulthood amid the backdrop of the Great Recession and the Covid-19 pandemic, student loans, stagnant wages and rising costs of living.

Nearly a third of older millennials have completely paid off their student loans, a feat that typically takes Americans about two decades to accomplish. But regardless of whether they're still making monthly payments, older millennials continue to feel the ripple effects of this debt burden. 

About 68% of older millennials, those born between 1981 and 1988, are still working to pay off their student loans, according to a recent survey conducted by The Harris Poll on behalf of CNBC Make It among 1,000 U.S. adults ages 33 to 40. Some are closer to payoff than others: about 11% report having paid off nearly all of their loans while nearly 40% have over half of their total balance still left. 

Many of those approaching middle age say the effects of these monthly student loan payments are far-reaching. Roughly a quarter of older millennials say student loans affected their ability to buy a home, as well as save for emergencies and retirement. Nearly 1 in 5 say they weren't able to take risks with their careers while about 17% said they had to live with family or friends because they couldn't afford their own rent and student loan payments. 

"Older millennials, while largely content in life, are stuck with one foot in the future and one in the past," says Harris Poll CEO John Gerzema. This cohort is moving out of their 30s, into middle age and becoming more established — settling down, owning a home, moving up in their careers. Yet they're still held back by the past thanks to student loans and expensive living situations that make them unable to save for the future. 

Student loans helped push back marriage

For Richard Williamson, 34, the approximately $18,700 student loan balance that he's still paying off 11 years after he left college is an especially bitter pill since he never finished his degree. "I'll probably always regret not getting my degree at the end of day. I was the crown jewel of my family. And I just fell off a hill somewhere," Williamson says, adding that he thinks it's too late for him to go back to college. 

Williamson attended NYU's Polytechnic School of Engineering, but when his mother died, he withdrew in 2010 to help his family. "I had to support my little sister. Before then, I was doing a work-study program, but I had to get a regular job," Williamson says. 

More than a decade later, Williamson is now a senior designer at a utility company earning over $100,000 a year. While he has built a successful life in Brooklyn without a degree, he feels his student loan debt held him back. He met his future wife, Vanice, in 2014 at age 27, for instance, but they didn't marry until June 2019. They're just now beginning to try for children, a decision delayed mostly because of his debts. 

"If I didn't have that debt, we would have had kids already. We'd have been married probably by the time I was 30 or 31. My life would have been way farther ahead than it is right now," he says. 

Student debt delayed families

About 45 million Americans carry some student loan debt. Among older millennials who attended at least some college, nearly 4 in 5 took on some type of debt to finance their higher education, borrowing an average of $21,880, according to The Harris Poll and CNBC Make It survey.

Of older millennials who are still paying down their student loans, the median monthly payment is $200. But many are paying much more. Shalae Morgan, 35, was paying about $900 a month on her loans after borrowing about $200,000 in total for a bachelor's in biology from Alabama A&M University and a master's degree in microbiology. 

That debt changed the course of her life, Morgan says. She joined the military after school, in part because she was offered $50,000 toward her student loans. She was deployed to Afghanistan in 2013 and Kuwait in 2017. 

After Kuwait, Morgan came home and really started working to pay down all her debt, including her student loans, $50,000 in credit card debt and a $15,000 car loan. Four years later, she and her husband, Myles, are debt-free — including the mortgage on the four-bedroom, three-bathroom home they purchased in 2014 for about $120,000. 

Yet that achievement came at a price. Morgan and her husband will celebrate their 10th anniversary this fall, but they've delayed starting a family.

"How could we bring the child into this world when we couldn't even afford to take care of ourselves?" Morgan says. "We'll just have to be the parents in preschool with our canes and our walkers. But at this point, that is when we could afford to have a child."

Student loans discouraged taking risks

So far, experts have noted that many millennials have simply delayed life milestones rather than forgo them. But time will tell if this holds true as this age group moves into a more expensive phase of life. 

Student loans are not the only factor making achieving life milestones more difficult, says Rachel Fishman, deputy director for research with the Education Policy program at New America. "It's a confluence of so many factors where I think millennials are really feeling the squeeze," Fishman says. "It's gotten more expensive to raise children. It's gotten more expensive to own a house. Wages have stagnated."

Historically, hitting 40 is a time that can be marked by a sense of scarcity, even without the burden of student loan debt, says Julie Miller, a research scientist at the MIT AgeLab. "At midlife, at least historically, that's where many people are financially squeezed between saving for their futures and saving for their children," she says. 

Adding student debt to an already expensive time can "put people in very precarious situations," Miller adds. That could mean lower lifetime savings rates for retirement and less opportunity to build wealth. 

That can carry over to relationships, Miller adds, saying that may be one more reason why millennial marriage rates are lower. "There are really huge implications for how loans and relationships come together," she says. If one partner has student loan debt, there are conversations and decisions that need to be made about how to treat that debt, she says. 

But student loans may also offer some positive outcomes as well, such as increased financial literacy. "Older millennials are kind of pioneers in figuring out how to navigate, largely without the help of parents, how to build up their own financial savvy," Miller says. 

Unfortunately, sometimes those lessons mean millennials feel that they can't take professional or personal risks. Jade Cephas, a 37-year-old data analytics associate, says she decided to work at a bank rather than in a more creative career because she needed stability. "It's hampered my creative side, and I feel like I'm forced to kind of be a worker bee at a corporation because of the fear of not being able to support my household on a creative salary," she says. 

Cephas bounced around a bit while attending college, enrolling in a couple private universities and taking out about $90,000 to finance her degree over the course of five years. Pregnant with her son when she graduated in 2006, Cephas found a stable job at a bank and lived with her mother until 2009, eventually buying a home in 2017. 

Although Cephas has moved up the corporate ladder over the years and makes about $95,000 annually, she still has about $77,000 left on a mix of federal and private student loans. She says she wants to pay off her loans in the next five years, not just so she can have more financial freedom, but so she can start helping pay for her son's college education — even if that comes at the expense of her own future and retirement savings. 

"It's sad that we have to make that choice," Cephas says. "I want to be financially stable enough to pay for his college and not set him up to be paying student loans for 20, 30 years like I have been. My loans are older than he is." 

CNBC Make It will be publishing more stories in the Middle-Aged Millennials series around student loans, employment, wealth, diversity and health. If you're an older millennial (ages 33 to 40), share your story with us for a chance to be featured in a future installment.