Have you ever missed a credit card payment? Fun fact: Your payment history makes up 35% of your credit score.

After your payment history, the other thing that can really ding your financial health is credit utilization — if all of your cards are maxed out, it can hurt your overall credit profile. 

Credit scores matter a lot because they are a gauge lenders, credit card companies and landlords use to measure how you manage debt and how likely you are to pay back money you borrow. 

“Your payment history is the single most important factor in credit scoring, and a single payment made 30 or more days late can knock 60 or more points off your credit score,” says Matt Schulz, chief consumer finance analyst at LendingTree.

I racked up some credit card debt years ago. It wasn’t crushing, and I don’t recall missing any payments, but just knowing I had a balance made me nervous. I paid it off as soon as I could.

Yet even a single missed payment can cost you and derail major life goals. Here is how one middle school teacher I spoke to got his credit back on track.

If you’ve fixed your credit score — or want expert advice on the best way to do it — I want to hear from you. Write to me at onthemoney@thomsonreuters.com.