When you think about retirement, it’s generally a time later in life after you’ve put many working years into a career. But today, some people are retiring in their 40s, 30s, and even in their 20s! What is the secret to retiring so early?

I reached out to several bloggers who either retired or reached financial independence by the time they reached their 30s to learn just how they did it.

Even if you are not aiming to retire at a very young age, these strategies can still help you accelerate your retirement.

Secret 1: Pay down debt ASAP

The first step toward early retirement is to get rid of debt as soon as possible. Making payments on debt limits your ability to build your investments and grow enough assets to retire. This is how Michelle Schroeder-Gardner of Making Sense of Cents got started on the path to financial independence in her early 20s. “In the beginning,” she said, “I worked many, many hours a week so that I could pay off my debt in seven months, but it was well worth it.”

See also: The Fastest Way to Pay Off $10,000 in Credit Card Debt

Secret 2: Take advantage of compound interest

The key to reaching early retirement is to save a large portion of your income — for example, 50 percent or more — and let that money compound over time. How can you put away that much on a modest income? You need to live very frugally so you can apply a large percentage of your income toward investments.

Jeremy Jacobson, who runs Go Curry Cracker with his wife Winnie, reached financial independence in his 30s. He explained, “We just used our income to buy our freedom rather than things and experiences that we would have quickly forgotten. Ironically, thanks to compound interest we can now have things, experiences, and freedom.”

Secret 3: Multiple sources of income

Many of these bloggers who retired early had a traditional career for a time, and gradually built up “side hustles” to generate multiple streams of income. The extra cash helps get debt paid off faster and starts building your investment accounts sooner. Writing, owning income properties, selling items on eBay or Amazon, and consulting are some ideas to bring in “extra” money.

One of these side projects that you enjoy could grow into enough income to one day replace your primary job. (See also: 15 Ways to Make Money Outside Your Day Job)

Secret 4: Commit to living differently

One thing I noticed is that these people are quite different from their peers. They are not concerned about fitting in and even celebrate living much differently than others their age.

Travis Hornsby, blogger at Millennial Moola, was able to retire in his mid 20s. How did he manage it? “I lived in a semifinished basement for several months because it included utilities and allowed me to supercharge my savings rate,” he explained.

Justin McCurry at Root of Good retired in 2013 at age 33 by redefining what qualified as a sacrifice. “Unlike our peers, we never upgraded our starter home to a McMansion, nor did we trade in our Honda sedans for luxury cars,” he said. “Is that a sacrifice?”

Kristy Shen, one half of Millennial Revolution and retiree by age 31, resisted the pressure to buy a large home and settle into a traditional lifestyle. “We stuck to our guns because we knew the math didn’t make sense,” she said.

Secret 5: Know when to stop

Many of those who retire at an early age plan to maintain a low spending rate after they retire, allowing them to leave the…