When Robert and Sara Roose got married in 2014, they began to consider what it might look like to never have to work again — and what number in their bank account could make that possible. As Robert puts it, “I’ve never been a fan of waking up and going to work and exchanging time for money.” They were living in Australia and supporting themselves through the internet: She was running a nutrition blog, while he did online marketing. In 2016, the couple moved to San Francisco, the city with the highest tech salaries, where Robert took his first full-time job as an engineer at a big-data company, making $180,000 a year. Sara continued her blog and started a consulting business. Since then, they’ve tracked the price of groceries on spreadsheets and logged every purchase, saving 70 percent of their income. After projecting their monthly cost of living, the Rooses determined they’d need $300,000 in investments to be able to live off the dividends. Within two years, they plan to hit this “magic number,” after which they’ll quit their jobs and roam the world.

Sara and Robert, now 23 and 27, are part of the Financial Independence, Retire Early movement, or FIRE. Born in the exuberance of the first dot-com boom, it gained momentum during the financial crisis. The central tenet is self-reliance: By maximizing earning and minimizing spending, nearly anyone, its enthusiasts believe, can retire decades early. Reddit threads and blogs serve as FIRE’s playbooks. One such site is Mr. Money Mustache, written by a software engineer who retired at 30. On its forums, 38,000 users discuss everything from the pragmatic (“Advice on maximizing house sale value”) to the personal (“How to convert your significant other in 50 awesome steps”).

The FIRE community has its own taxonomy. People on the “Lean FIRE” side of the spectrum live minimally like the Rooses (their San Francisco apartment has three plates, bare walls, and a mattress on the floor). They set lower magic numbers and plan to take their dollars to a cheaper country. On the other end of the spectrum is “Fat FIRE”: high-income professionals who live like interns so they can enjoy an upper-middle-class retirement. Daniel Imberman, a 26-year-old software engineer, drifts toward this pole, though he rejects the FIRE label (“sounds like classic tech-douche”). His target is $15 million.

“Being rich has been on my mind since I started working in tech, but the thought that you could get rich enough to stop working only came to mind once I got to Silicon Valley,” Daniel says. Riding the wave of entrepreneurial excitement, he designed a three-fold plan of which he’s currently in the first stage: (1) learn from his job while building a startup fund of $500,000, (2) eventually launch a small company to generate passive income or sell for a profit, and (3) accumulate enough to quit working and become either a musician or an angel investor.

When Daniel first decided to engineer his early retirement, he obsessively checked his Mint.com account and agonized over every dollar: Could he spend $10 on an Uber or $20 on dinner with friends? “I was wasting brain cycles,” Daniel says. So he decided to automate the decisions. Each payday, his checking account funnels money into various other accounts: one for consumer electronics, another for a house, a “stupid fund” for wasteful spending. Every quarter, Daniel schedules a “management” meeting with himself; he answers a questionnaire he developed to evaluate his career, fitness, friendships, and love life. “Who are you right now?” the form asks, as well as, “Who do you want to be in six months?”

“I have this large-scale plan guiding me,” Daniel says. “But on a day-to-day basis, if I do what my phone tells me, I’m heading exactly in that direction.” Like many other aspiring early retirees, Daniel also made lucky investments in cryptocurrency. “The crypto lottery forwarded my timetable by five, ten years.”

And then there are those like 24-year-old Jordan (she asked that we change her name), who see saving as the only way to secure freedom. In college, Jordan studied computer science — a track everyone said would ensure a good income. A teenager during the financial crisis, she quit her expensive dance lessons and took free coding classes instead. It had pained her to see her father out of work and her parents struggling to support their seven children. But tech wasn’t as stable as she’d hoped; seven months into her first startup job in the Bay Area, Jordan was laid off. After four months of unemployment, she was about to move back to the Midwest when she was hired as an engineer at Lyft — the only black woman on her team. This was summer 2017, around the time James Damore circulated an internal memo arguing that Google’s diversity tactics discriminated against white men. “It’s hard to be sane, occupying these two radically different landscapes,” Jordan says. There were her ethics (“anti-consumerist, anti-capitalist, for social good”), then there were the values of her industry (“tech just tries to get us to do and buy things”). “I enjoy being an engineer,” she says, “but I’m not going to be able to last.”

She spent three months plowing through FIRE literature — financial independence blogs and subreddits, a book called I Will Teach You to Be Rich. She learned about passive index funds and tax allowances and backdoor Roth IRAs. The typical FIRE devotee is a young, white male, so the process took customization; she rejected, for example, the community’s wardrobe advice (“I’ll never have to buy another T-shirt in my life; I have so many from various promotions, athletic events,” one man wrote). Jordan moved out of her $2,070-per-month apartment in San Francisco to a cheaper room down the street, sold 80 percent of her clothes on Poshmark, got into Bitcoin, and set up automatic retirement contributions.

“There are ways of doing things and understanding the world that our generation is turning on its head. We don’t trust the systems in place,” Jordan says. “I don’t know, for example, how much I’ll get in social security. If you come from where I come from, you know that things can change overnight.” She aims to reach $720,000, and financial independence, by age 35. Then she plans to dance. Maybe even work retail or learn a new language.