The topic of retirement is hot. In fact, it's on "FIRE".

Don't quite get the reference? "FIRE" stands for "financial independence, retire early," which has become a booming movement for the past few years. However, it takes determination and planning to permanently ditch your day job. And that's especially true if you're in what's traditionally considered the early-to-mid career level.

Let's face it: Saying goodbye to the daily grind isn't without its challenges. You have to be pretty focused on your goals to make it work, not to mention highly self-disciplined. Nevertheless, with a little forethought, you might be able to hang up your professional hat in your 30s or 40s without giving up life's comforts.

Sound like a winning solution for you and your family? If you're serious about embracing a FIRE attitude, consider taking these steps to save up for an early exit.

1. Create a post-retirement budget.

How are you going to retire if you don't know what your budget will look like? You need to figure out how much money it will take to live on. Otherwise, you'll never be sure that your cash won't suddenly dry up.

Construct a worksheet that includes how much you spend annually now. Then, start projecting into the future. Keep in mind that your cost of living will change as you get older. Try to factor in inflation so you're fully aware of what to expect.

Having a post-retirement budget gives you a super snapshot of how much you'll need at a baseline level before handing in a resignation. For instance, say you believe you can live on $60,000 a year. If you plan on retiring at 35, you can expect to live for about 45 more years based on life expectancy charts. That means you'll need at least $60,000 times 45, or $2.7 million total. And you'll probably want to have even more.

2. Set up a formal retirement plan—pronto.

Having money in your savings account isn't going to be enough to carry you through four or more paycheck-less decades. In order to successfully free yourself financially to confidently give your boss the boot, you need to invest in a retirement vehicle.

What type of vehicles works best? A great one is a small business 401k, which is becoming more prevalent as a corporate perk. Even startups have been known to offer their crews the opportunity to drop tax-free cash into 401ks. Plus, lots of employers will match 401k contributions up to a certain dollar or percentage of salary.

Of course, you'll need to figure out how much to stash in a retirement account that won't be available to you until later in life. The best rule of thumb is to sock away as much as you reasonably can. That way, your investment money will be waiting for you down the road.

3. Live frugally today—and forgo little luxuries.

To be able to put money into your retirement vehicle and liquid savings, you can't subscribe to the "live it up" mantra. You're going to have to control your spending, right down to the nearest penny. If that seems too difficult, or you can't give up your morning lattes, you probably aren't going to be able to retire as early as you'd like.

There's no need to live in an unheated shed in someone's backyard. But you probably don't need a huge apartment or home, or to drive a new, luxury sports car. Before making any unnecessary purchases, remind yourself of your ultimate objective: getting out of the rat race fast.

Remember that making this sacrifice today isn't for nothing. Paring back your expenses when you're younger teaches you how to get by with less. It also sets you up to have extra cash on hand for emergencies, or even to invest in long-term mutual funds or stocks.

4. Get into a lucrative career field.

It's no secret that some careers can be incredibly high-paying compared to others. These alternative fields can also secure attractive salaries, although they come with the expectation that you'll work your tail off. As long as you're willing to go all-in, secure the most lucrative job you can get. After all, you'll only be working for around 15-20 years instead of the normal 40+ years.

This may mean forgoing some of your professional dreams, especially if your dream role is in an industry that doesn't pay as well. However, you may still be able to retire earlier even if your salary isn't strong.

What should you do if your paycheck is paltry? Reduce your living expenses as much as you can. This may mean relocating to an area of the country that's safe and not expensive. That way, you can still squirrel away significant funds despite your modest income.

5. Embrace a side hustle.

Tens of millions of people have joined the thriving gig economy, and not just because they need more money now. Like you, plenty of them are using their side hustles to stock up for the future.

Gigging during the nights and weekends can be a smart way to supplement what you're currently making. Additionally, you'll have the chance to expand your expertise and network. Who knows? You might end up enjoying your gig so much that you wind up making it part of your retirement lifestyle.

Though lots of gig economy jobs are outside the home, some are available online. Being able to perform remote project work gives you the independence to work whenever you like. Just be diligent about putting your hustling money into a dedicated account that you're not going to touch until retirement.

Getting all "FIRED" up to give yourself a retirement party when most people are just starting out? You can do it, just like so many others unwilling to accept the status quo. You just need to fuel the flames with some practical planning.