My favorite Oprah quote is: “When people show you who they are, believe them.” This one sentence can change your world. You can spare yourself grief and aggravation. You can save time. And you can dramatically improve (or even save) your life.

I learned Oprah’s quote the tough way. I was dating a guy exclusively and he asked me to go on a cruise with him. We each paid for our own plane tickets to get to the cruise. We paid for our own cruises. About to board the ship, we were asked for a credit card to pay for drinks onboard and incidentals. He had me go first—meaning he wasn’t buying my drinks either. I was deflated. I didn’t mind buying my own cocktails; I did mind what it meant. He was showing me he wasn’t into me. (And he was cheap!) Part of me wanted to turn back and skip the cruise, but I decided to make the best of it and realized I had a decision to make when I got home.

When people show you who they are, believe them.

A few years out of college, I rented a house with a friend. I didn’t know her extremely well, but she was fun and we both loved to go out dancing at a club up the street. I thought it was the perfect situation for two twenty somethings, friends who could split the rent and expenses. Soon, a different picture of her emerged. She received late notices on bills in the mail. She didn’t always have her half of our rent. Bill collectors left her messages. It got worse. She wrote some bad checks. She skipped out on her court date. One day, she just vanished. I heard she left her car—about to be repossessed—abandoned on a street. She was showing me who she was all along. She wasn’t just someone late on her bills. She was someone who manipulated people, lied, and walked away from her responsibilities.

When people show you who they are, believe them.

If I knew long ago to immediately trust what I was seeing—to believe people as they reveal who they are—I could have made a lot of decisions faster. I could have skipped chronic analysis and the polling of my friends. I could have ditched my eternal hope that people must be better than what I was witnessing with my two eyes. They weren’t better. They were exactly who they said they were in words and actions. I could have ended relationships quicker, saved time and torment, and increased my self-respect if I trusted what I saw.

In other life situations, believing people is a lot more serious than a boyfriend who isn’t into you or a roommate who is a few sandwiches short of a picnic.

If you believe people when they show you who they are, you quickly know someone who hits you is an abuser. You don’t say that person had a bad day, messed up once or will never do it again. Abuse is a billboard you don’t want to test.

If you meet someone addicted to drugs, it’s not someone going through a bad patch or partying a little hard. It’s someone saying, I am a drug abuser. I am an addict.

If someone married or in a relationship hits on you, it doesn’t mean you’re special, it means he lacks character, integrity and is a cheater.

You realize when a friend insults you or takes little digs here and there … that person is not really a friend at all.

As soon as people put up their billboard …
I am cheap.
I am not into you.
I am addicted.
I abuse.
I cheat.
I am rude.
I am negative.
I am exploitative.
I am disloyal.
I am selfish.
I’m not really a friend.

Believe the billboard.

You don’t have to watch much news, Dateline or 20/20 to know that some people would still be alive today if they believed the billboard. Most people could at least save themselves some anguish.

As the legendary philosopher Jim Rohn said: “You must constantly ask yourself these questions: Who am I around? What are they doing to me? What have they got me reading? What have they got me saying? Where do they have me going? What do they have me thinking? And most important, what do they have me becoming? Then ask yourself the big question: Is that okay?”

People give you clues as to who they are all the time. Now all you have to do is believe them—the first time. Or as author Iyanla Vanzant says, “When you see crazy coming … cross the street.”