Now that I’m frugal, it’s hard not to look back on the choices I made in the past with regret. Luckily, I came to my senses pretty early in life. I could have done a lot more damage throughout my 20s if we hadn’t decided to change our lifestyle before we got married. But I’d be a lot better off if I’d avoided the mistakes I made in my teens and during college.

In the hopes that others may learn from my mistakes, here are the biggest financial mistakes I made before and during college:

I didn’t save for college.

I got my first part time job at 15 years old. I paid for my own car insurance and gas, but other than that I had no bills or responsibilities. I didn’t save a single penny. Where did my money go? I blew it on stuff that I didn’t need.

What I learned: Plan ahead for the things you want. We’re saving now so we can pay cash for our trip to Europe, we’re already saving for retirement, and we’ll start saving early for our children’s college educations.

I didn’t apply for scholarships.

I only applied for a couple scholarships. My grades were above average, and I was active in the school newspaper. If I had taken scholarships more seriously, I would have qualified for at least a few.

What I learned: A little extra work can save you a lot of money. Scholarship applications are the college equivalent of coupons, menu planning, and other frugal pursuits.

I took out private student loans to cover living expenses (and lived extravagantly).

My parents paid my rent, and federal loans covered my tuition. I was responsible for food, car insurance, and utilities. My job at the student newspaper took up a lot of time, but I managed to work part-time my junior and senior year. If I had worked more and lived frugally, I wouldn’t have needed to borrow high-interest loans. Now I’m stuck paying $20,000+ at 8%.

What I learned: Don’t borrow to live a lifestyle you can’t afford. It also taught me the importance of fully understanding all of my financial decisions before making them. I didn’t know what I was getting myself into, and now I’m paying the price. I wish I could take back my decision, but I’m stuck with these loans. Forever.

I ate out constantly.

At least 75% of the money I spent in college went to restaurant food. This wasn’t good for my bank account or my health.

What I learned: Eating out is expensive and unhealthy! Not only did I drain my bank account, but I gained weight. I appreciate how little we spend on food and how much healthier we are now that we menu plan and buy groceries.

I charged up credit cards and only made minimum payments.

Some of my credit card debt was due to a car that broke down every other week one summer. I didn’t have the money to pay for the repairs, but I had an “emergency” credit card.

Only $1,000 of my $5,000 in credit card debt went to car repairs, though. The rest? Couldn’t tell you. I have no idea where that money went. Probably pizza, clothes, DVDs, and bar tabs. I never missed a payment, but I only sent the minimum. It wasn’t until I graduated, after three years and who knows how much interest paid, that I got serious about paying them off.

What I learned: Plan ahead for emergencies and avoid credit cards. I lived in fear that my car was going to break down because I knew I didn’t have money to cover it. I feel so much better now with an emergency fund. It also taught me about interest rates. You can make minimum payments for your whole life and never make any headway. I’ll apply this lesson someday when we have a car payment and mortgage.

It could have been a lot worse. I had friends with twice as much student loan debt and $20,000 in credit card debt. Yikes.

What are the worst financial mistakes you’ve made and what did you learn?