Pensions are disappearing. The future of Social Security is uncertain. It's likely we'll live longer lives.

But most Millennials still aren't putting away any money for retirement.

About 66% of people between the ages of 21 and 32 have absolutely nothing saved for retirement, according to a report from the National Institute on Retirement Security.

CNN heard from dozens of Millennials about why they have little or nothing saved. For the most part, they believe they'd be better off putting their money elsewhere.

Some want to pay off student debt. Some are trying to build up their own business. Many graduated during the recession, worked low-wage jobs for a few years and then went back to school to improve their job prospects.

Calculator: Are you behind on retirement saving?

For others, there are more immediate costs like child care and rent. They're still building up emergency savings and the idea of putting money in an account they can't touch for 30 years doesn't make a lot of sense to them, despite the advantage of compounding interest.

Here are four of their stories.

Focused on student debt

"I worry about retirement. I do think about it. But it's just so far away. There are so many other things that can happen first," said Alexis Nunley, 26.

She and her husband have prioritized paying down their student debt over saving for anything else. They've managed to pay off nearly all of their $60,000 of debt in just a few years by living with his parents and expect to move out this spring.

"We wanted to throw all our money at it," she said.

But Nunley said she is unsure if saving for retirement will become a priority, even after the loans are paid off. They'd like to buy a home and Nunley has been thinking about returning to school. After graduating with a degree in anthropology, she wasn't able to find a job in the field. She currently teaches at a pre-school.

"Ideally I'd like to retire on time. My husband and I have dreams of getting a small ranch in a mountain town. But I'm not sure yet if that's ever going to happen," Nunley said.

Related: Should I pay off my student loans early?

Saving without a 401(k)

Walter Stern, an electrician, started saving for retirement as soon as he was eligible for an employer-sponsored plan — but that wasn't until age 30.

His former employers didn't offer a retirement plan. Stern had to work two years at his current job before he was eligible for a SIMPLE IRA. His employer matches his contributions up to 3% of his pay.

"It's hard to turn down a match," said Stern, now 31.

About half of Millennials don't have access to an employer-sponsored plan, but that doesn't mean they can't save for retirement. Traditional IRAs and Roth IRAs offer tax advantages as long as you don't touch the money until age 59 ½.

But to Stern, putting aside money for retirement wasn't worth it before he would receive a match. First he wanted to pay off his credit card and student debt. He and his wife also have a mortgage and two kids under the age of three. Child care costs are their biggest expense, he said.

Despite his little savings, Stern remains optimistic about being able to retire. His wife works at a hospital and is paying into a pension.

"I have quite a few years left to work," he said.

Related: 66% of Millennials have nothing saved for retirement

'I've consciously decided not to'

Ken Chester Jr., 32, has about $8,000 in his bank account. But like a lot of his income, much of that will go toward his business ventures instead of saving for anything else.

"I don't disagree that modest savings toward retirement is a positive goal, but I've consciously decided not to," Chester said.

One of his businesses helps international students, immigrants and refugees connect with their new communities. Another aims to tackle college affordability.

"If I were to wait until I was older and more financially stable to pursue these passions, it might be too late," he said.

His passion projects don't pull in a lot of money, so Chester picks up contract work to make ends meet. It's sometimes a months-long contract as a speech pathologist at a school, the kind of job he went to college for. He also finds work advising Chinese students planning to study in the United States and mentors other entrepreneurs.

As a contractor Chester doesn't usually receive benefits. He buys health insurance off the state exchange. Even if he is offered a retirement account, he chooses not to use it.

But Chester isn't worried about what will happen to him in retirement. He's hoping at least one of his ventures is successful, and doesn't intend on retiring in the traditional sense anyway.

"Even if I made a lot of money, I don't want the do-nothing lifestyle," he said.

Related: Will I ever be able to retire like my Grandma?

Finishing graduate school at 29

Karissa Sampson, 29, recently finished a physician assistant graduate degree program and will soon start a new job at a family practice.

Before she went back to school, Sampson worked as an EMT for a few years. She opened an employer-sponsored retirement plan and contributed a little bit at the time. She doesn't think there's more than $600 saved there, though she hasn't looked at it in years.

"After basic expenses, I had about $40 left over each month. Sometimes I could save it, but sometimes, you know, your car needs new brakes," she said.

Now, she has about $190,000 in student debt to pay off.

About half of her take-home pay will already go to a minimum monthly loan payment, and she's not sure whether any extra money should be saved for retirement or used to pay down her debt faster.

"Honestly, at this point, I plan to put it all against student loans for a few years and then start saving heavily for retirement," Sampson said.

Related: This is how much student debt will cost you in retirement

She'll be eligible to participate in her employer-sponsored retirement plan after one year of employment and expects a 5% match.

"I know I'll be relying on my own savings for retirement, but I'm optimistic I'll be able to retire before the age of 65, barring any large unexpected expenses," she said.