After I retired from running, I was a counselor for 20 years at several schools in Southern California. At first, no one knew I was an Olympian who'd made international news for raising my fist on the medals podium in 1968 — not the district, and definitely not the students.

One morning I spotted four kids sneaking out of the school building, trying to play hooky. I ran after them, and I was right on their butts. Then they turned a corner and disappeared. At first I didn't know where they'd gone. And then, from the bushes, I heard one of the kids saying to the others:

"Man, who the hell is that old man? He can run."

When I told them to come on out, they asked me, "Who are you?"

I said, "Maybe if you was in school, you might look up one day and find out who I am."

A year later the very same kids came to me with a history book. They said, "Man, we see this picture in the history book and they don't have any story about it. It's just a two-liner with the people's names. We see this guy with your name. Were you in the Olympics?"

I said, "I'll tell you what. You guys go back and research it. Then come back and we'll have a discussion about it one day."

That right there is a pretty good illustration of how I've approached my fame as an athlete. Ever since I was a teenager and realized I was good at running, I wanted to use my skills as a way to help people.

Why I protested on the Olympic podium

That was the same attitude I had in 1968 in Mexico City. Before the games, some other athletes and I tried to organize a mass boycott to protest the International Olympic Committee and the low numbers of black coaches at the games. It didn't work, but I still wanted to make a statement.

So after Tommie Smith and I came in first and third in the 200-meter race, we went to the medals podium without our shoes on. We were both wearing black gloves on one hand. And when we stood on the podium, we lowered our heads and raised our fists in protest.

I'm really frustrated with a lot of today's stars, who have an opportunity to speak up but don't

I don't care what your ethnic background was, how much money you had in the bank, or how much money you didn't have in the bank, whether you lived in the hills, or whether you lived in the gutter. It didn't matter. You never saw anything like that before.

As soon as we raised our hands, it's like somebody hit a switch. The mood in the stadium went straight to venom. Within days, Tommie and I were suspended from the US Olympic team and had to leave Mexico City early.

The aftermath was hell for me and my family

The first 10 years after those Olympics were hell for me. A lot of people walked away from me. They weren't walking away because they didn't have love for me or they had disdain for me. They were walking away because they were afraid. What they saw happening to me, they didn't want it to happen to them and theirs.

My wife and kids were tormented. I was strong enough to deal with whatever people threw at me, because this is the life I'd signed up for. But not my family. My marriage crumbled. I got divorced. It was like the Terminator coming and shooting one of his ray guns through my suit of armor.

Still, I wouldn't change what I did.

That picture of me and Tommie on the podium is the modern-day Mona Lisa — a universal image that everyone wants to see and everyone wants to be related to in one way or another. And do you know why? Because we were standing for something. We were standing for humanity.

Why black celebrities have to be activists

People said, "Man, that's a courageous thing you did." Yeah, well, I have the same dang ingredients that you have. You just have to find yours within yourself.

I say to them, "Do you think Rosa Parks didn't have fear when she moved up a seat on that bus? You think Gandhi, sheet wrapped around his body, with the best thing he had for his protection those wire-rim glasses — do you think he didn't have fear?"

Fear is all around anyone who's trying to make change. But the men and the women of this world step through fear and challenge this system so other people can have a better life.

And so I'm really frustrated with a lot of today's stars, who have an opportunity to speak up but don't. They think they're secure in their little bubbles of fame and wealth. They think racism and prejudice can't touch them because they've achieved a certain level of success.

I want to tell them, "Your mother's not secure in that bubble. She doesn't have a tattoo on her forehead that says she's part of your lineage. Your son is not secure. Your daughter is not secure. Your father is not secure. The kids you grew up with are not secure."

Look at Deion Sanders's son: A few years ago he tried to use a credit card at a fast-food restaurant, and they called the police — they couldn't believe it was his credit card.

If you're famous and you're black, you have to be an activist. Activism is a guy who says, "I'm a multimillionaire, and I'm going to help." Activism is transparent.

Muhammad Ali is a great example. Ali didn't give his money behind closed doors. He didn't say, "I'm going to give this money to this group, but don't tell nobody." He went and said, "I'm helping here. I'm helping here. I'm helping here. I'm helping everywhere. Not because I want people to think that I'm some hotshot. I'm doing it publicly because I want you to know that you can do the same."

That's what I've tried to do my whole life. And I've seen it pay off. Those kids I chased when they tried to play hooky came back to me as adults and said, "I'm glad you got me to pay attention."

John Carlos is a medaled USA Track and Field Hall of Fame athlete and Olympian. After his running career ended, he went on to play in the NFL and the Canadian Football League and worked with Puma, the United States Olympic Committee, and the organizing committee for the 1984 Summer Olympics.

Learn more at johncarlos68.com. He is also on Facebook, Twitter, YouTube, and Instagram.