40-year-old self-made millionaire: 5 frugal habits I'll never quit

I was raised by a single mom who was careful about money. She scrupulously saved, clipped coupons and held onto furniture and clothes that would not have looked out of place in an 80s movie.

After I got my first job, I earned a decent salary as a software engineer, but I realized that I had inherited my mom's scarcity mindset. I always felt worried or guilty about money — and a lot of it was just going to our basic living expenses and paying off my wife's student debt.

My approach to money changed in 2019, when my wife and I started talking seriously about what kind of future we wanted for our two young kids. We wanted to build wealth so that they could afford more opportunities in the future. 

DON'T MISS: How to master your money and grow your wealth

We educated ourselves and made a plan with help from a financial advisor. We started investing in real estate, acquiring three rental properties. And in 2020, we launched a personal finance website, Parent Portfolio, to help other families like ours. 

At 37, my net worth had reached a million dollars. Although I hit this financial milestone, there are some frugal habits that I will never give up: 

1. I'm a regular at my local library

Our local library is a wonderful place to spend an afternoon. It offers so many fantastic free resources that many people may not be aware of. 

In addition to borrowing books, my family has used our Omaha library's 3D printer and checked out board games as well as podcast equipment. 

We've taken advantage of some great community activities, like baking classes, art tutorials and basic self-defense training. 

No matter how much money I make, I will always make sure that I have a library card.

2. I brew my own coffee

Like many people, I have a cup of coffee every morning. But buying it every day can quickly become an expensive habit, which is why I still like to make it at home. 

I will get a $16 bag of coffee grounds from the grocery store — which will last for at least two months — and set up my coffee machine the night before to brew coffee the following day. This routine saves me money and time getting ready in the morning.

For the record, I'm definitely not against buying coffee. My wife and I will budget for it every month if we want to randomly sit down at a coffee shop while we're out.

But my home set up definitely isn't going anywhere. 

3. I still do DIY repairs

If something breaks at home, I make an attempt to personally fix it first. To me, frugality isn't just about saving money, but taking care of the belongings we already own. 

For example, when my wife and I got married 13 years ago, we bought a dresser for our bedroom. There have been a few times when the drawer guide rails detached from the plastic meant to hold the dresser together. 

Rather than replace it because of this quirk, there have been several times where I've just drilled in screws wherever the plastic stopped holding up. 

For under a few dollars, I've been able to add more years to the life of the dresser, and ultimately save more money overall. 

4. I'm careful with my credit card

Even though I am less stressed now about being able to afford the things my family wants and needs, I still never want to depend on a future paycheck for a purchase I'm making in the present.

Thanks to that mindset, I'm still very cautious about my credit card usage.

I always pay off the credit card balance every month to avoid paying additional interest. I only borrow money from a credit card if I know that I have already budgeted for that expense and I'm certain I have the cash readily available in the bank.

I pay close attention to what credit card points we have available to us and how to best apply them, whether that is exchanging them for free flights and a rental car, or using them to get gift cards that allowed me to replace a decade old 20-inch TV with a brand new 4K model.

5. I only buy used cars

My wife and I have never been big car people, and we try to keep our cars as long as possible. We have a 2005 Saturn Vue and a 2013 SUV. Both have over 100,000 miles on them. 

We invest in regular car maintenance and do our due diligence when things start to show wear and tear. For example, when one of our cars needed a new transmission, it turned out that it was actually more cost-effective to replace the car entirely. 

So I researched online and weighed different factors like mileage, year, prior accidents, and overall customer ratings, and found that used SUV with 80,000 miles already on it. We still have that car three years later.

Why these habits are so important to me

When I look back at my upbringing, I am reminded of a quote by the late computer science professor Dr. Randy Pausch: "Engineering isn't about perfect solutions; it's about doing the best you can with limited resources." 

Growing up, I didn't have a lot, and I learned how to be creative with what I did have at my disposal. I think that informs a lot of the decisions I make about money today. 

I've never been about keeping up with the latest fashions or owning the newest tech gadgets. What I want to do is be able to spend our money on valuable experiences, whether that is learning a new skill or flying to visit our extended family. 

Ultimately, these frugal habits help us put our resources towards the things that matter the most to us. 

Jonathan Sanchez is the co-founder of Parent Portfolio, where he helps readers take control of their financial future and build wealth for the next generation. He was raised with frugal habits and by practicing wise money decisions, became a millionaire in his 30s. Follow him on Instagram and join his newsletter at Parent Portfolio.

Want to master your money this fall? Sign up for CNBC's new online course. We'll teach you practical strategies to hack your budget, reduce your debt, and grow your wealth. Start today to feel more confident and successful. Use code EARLYBIRD for an introductory discount of 30% off, now extended through September 30, 2024, for the back-to-school season.