Millennials are impacting the workforce in unexpected ways, requiring different behavior from their bosses, and forcing reconsideration of misperceptions about them. Now, they're busy redefining what it means to be retired.

Introducing the FIRE movement: Financial Independence, Retire Early.

Yes, it's a thing. Growing rapidly. Hundreds of thousands of millennials are reading blogs and e-books on the topic, a FIRE Reddit community has 426,000 subscribers and there are FIRE Facebook groups and websites. It has spread to London, where 900 people packed into a single pub to learn about the movement.

First, FIRE involves a redefinition of retirement. Kiplinger's says with FIRE, retirement means "Leaving the rat race for pursuits that offer more flexibility and control over how you spend your time--and never returning to a (stressful) 9 to 5 job. It's working just as long as you otherwise would, but on your own terms, creating work that provides value and aligns with your values". (Often in an entrepreneurial venture) Retirement redefined.

Many FIREwalkers (as they're called) are corporate refugees from high paying but high-stress jobs that leave behind their peak corporate earning years.

Accordingly, FIRE also requires scaling down your spending and lifestyle (to varying degrees). But as Pete Adeney, the movement's founder, said in Kiplinger's November issue, "It's not about living a terrible life of deprivation. It's about understanding what makes you happy and cutting down your spending on what doesn't make you happy."

With FIRE, there are typically one of two goals. The first is to reach financial independence by saving 50 percent or more of annual income over an extended period (10-20 years).
The other is to achieve savings equal to 25 times annual living expenses, which allows you to follow a general financial rule of thumb of not withdrawing more than 4 percent of savings during a decades-long retirement.

Let these goals sink in for a moment because that means saving a lot more and spending a lot less. That comes with lifestyle choices.

That said, there are several kinds of FIRE. Lean FIRE means living on less than $40,000/year, likely requiring some intense deprivation/frugality, despite what Adeney says. Barista FIRE is for those close to being financially independent but that still need a part-time job to make it work. Fat FIRE means saving enough to generate an annual retirement income of $100,000 or more. 

I'd add another kind, FIRE-lite. That's me. I retired early from corporate at the age of 48 (admittedly with a sizable nest egg) to pursue the life of an entrepreneur/speaker/author and to broaden my platform for making a difference. I make less now than in my fat corporate days (when you count in annual options I was getting) and have certainly left behind my top corporate earning years. While I still live a sizable lifestyle and still make quite a bit with my entrepreneurial venture, my wife and I have definitely cut expenses in some places (on things that don't make us happy) and plan to make further cuts later on.

All in exchange for an intoxicatingly more flexible, purpose-driven, healthier, lower stress, happier, yet still comfortable, life.

Whatever form of FIRE seems right for you, Kiplinger's offers nine tips to start making serious financial adjustments:

1. Determine why you want to achieve FIRE. Think about why you want this lifestyle and envision what you'll do when you achieve it (this keeps you motivated). In my case, I wanted more impact with my work, more independence, more family, less stress. Remembering this helped me get the courage to leave corporate.

2. Calculate your net worth (total assets minus liabilities) to see where you stand. A financial advisor can help you with this (and an entire FIRE plan).

3. Track every dollar spent so you know where your money goes. I promise you'll be shocked (we were) at how quickly things add up in areas that bring you no real joy.

4. Slash expenses. To reach a savings rate of 50 percent or more, you'll need to cut major expenses, including housing and transportation. That might mean no oversized houses or fancy cars, which there's nothing wrong with--it's just that you can't escape the need for real choices here. FIRE is not for those who want to keep up with the Joneses. It's about enabling a more flexible, independent, fulfilling lifestyle.

5. Pay off high-cost debt. like credit cards. Absolutely critical.   

6. Build an emergency fund. Experts recommend doing so in liquid, accessible form, like cash.

7. Take advantage of tax-friendly accounts. Like 401(k), IRA's, etc. This is the "smart money" part of FIRE.

8. Use index funds to keep investing costs low. "Smart money" part two.

9. Find a side hustle to increase income and savings. For me, my side hustle is actually a robust, full-time keynote/workshop/coaching business. For others, it may simply be a Blog they can monetize. In FIRE, you "retire" from a 9 to 5, but that doesn't mean you're retiring.

So maybe lighting a FIRE is just the spark you needed.