While many Americans are challenged when it comes to saving for their retirement (Forbes reports that just 14 percent of employees consider themselves to be on track), there are some who are way ahead of that curve. They’ve saved so much, in fact, that they’re not worried about being able to retire at, say, 65-years-old. They’ve already retired. At age 40. Or 35. Or maybe even 30.

Maybe you’d like to call this “speed retirement” or “extreme early retirement” or just amazing self-discipline. Whatever term you’d like to use, some people have managed to adjust their lifestyles so they can spend the rest of their days without worrying about money.

As Forbes notes, it may not be so much that they don’t ever want to work again – they may simply want the freedom to choose whether they work and how. Or maybe they want to perform the kind of service that won’t earn them a paycheck, such as volunteer work. Of course, some may just want to spend their time engaging in traditional retirement activities, such as traveling and spending more time with their families.

Todd Tresidder is one speed retiree who was able to leave the workforce 14 years ago at age 35. A former hedge fund investment manager, Tresidder now spends his time (as his Twitter bio puts it) as a “money coach,” a blogger and an author (his books include How Much Money Do I Need to Retire? and The 4% Rule and Safe Withdrawal Rates In Retirement (60 Minute Financial Solutions).

In a blog post for Early Retirement Extreme, Tresidder notes that, while living in Lake Tahoe running his hedge fund, he managed to save 50 to 70 percent of his earnings. And though he was up working before dawn, according to Tresidder, he’d spend his afternoons hanging out with ski bums, where he didn’t have to worry about “keeping up with the Joneses.”

Pete (he guards his last name for the sake of his family’s privacy) and his wife may not have had hedge fund salaries, but they still managed to retire at age 30 from their middle-income jobs. Now writing a blog called Mister Money Mustache, Pete tells The Washington Post that he achieved his goal through extreme efficiency. Rather than buying new cars, Pete – a onetime engineer –  and his wife kept driving old ones – or better yet, riding bicycles whenever possible. The family generally eschewed restaurants in favor of cooking at home. And income from stock dividends and a rental house was more than enough to fund the family’s needs, he tells The Post.

If, like these people, you’re looking for ways to move up the date for your retirement, here are some tips:

Curb the big expenses

 Yahoo! Finance offers the example of Olivia Campbell, a woman who isn’t that concerned with eliminating every little expense. Campbell tells the site that she still spends to go out and have coffee with a friend. But she puts a tight reign on her housing and transportation budget, allowing her to save 75 percent of her $90,000 salary. Yahoo also offers the example of another woman, Chanda Forrest, who lives in the U.K. and saves big by sharing a small apartment, which is in walking distance to the local amenities. Forrest tells the site that this helps her save 50 percent of her salary.

Picture your retirement

Imagining what your retired life will look like – whether that means working on occasion or spending your time traveling – can help keep you motivated now to help you save as much as you’ll need, according to Forbes. Plus, doing so will help you gauge how much money you’ll need to save to afford that lifestyle.

Do the math

 You’ll want to think ahead to figure out what kind of expenses you’ll have in your retirement years. As we explained here in an Ally Bank Straight Talk post this spring, there are formulas to help you figure this out. As we said then, AARP recommends that, by retirement age, you’ve saved nine times your annual salary. So if you’re retiring from a position that pays $100,000 a year, you should have $900,000 in your war chest if you want keep living the $100,000 lifestyle. AARP also offers a chart with guidelines as to how much you should have in savings at ages 20, 30, 40, 50 and 60, along with amounts for different incomes.

Be efficient with your taxes

 As Forbes notes, if you’re saving via traditional IRAs or 401(k)s, you’d probably have to pay a 10 percent penalty if you withdraw your funds before age 59½. To get around this, the publication offers several strategies, including converting your pre-tax money into Roth IRAs.

Even if you decide speed retirement isn’t for you, if nothing else, you can use these tips to help you shore up the retirement savings you’ll access when you finally do reach retirement age – that is, traditional retirement age.

At what age do you plan to retire? What steps are you taking to make sure you have a comfortable retirement?