In 2017, Bob Harper broke one of his cardinal rules.

The fitness guru who coached contestants on NBC’s “The Biggest Loser” through weight loss, while millions tuned in week after week to see the results, had failed to listen to his own body.

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“About six weeks prior to my heart attack I was at the gym and I fainted,” Harper, now 53, told Fox News. “That was very unusual – nothing like that had happened before but I made excuses. ‘Oh, I was dehydrated,’ or ‘I ate too much or not enough’ – all the excuses you can think of.”

But then Harper developed dizzy spells, which progressed to the point of a friend insisting he see a heart doctor before sending him home from the gym. Harper said he agreed on a Friday to see the doctor on a Monday, but on Feb. 12, the day before he was scheduled to go, he had a heart attack referred to as a “widowmaker.”

According to the Cleveland Clinic, the widowmaker heart attack occurs when the left anterior descending artery, which supplies blood to the larger front part of the heart, is blocked at its origin. From the outside, a patient experiencing a widowmaker will exhibit the same symptoms as a heart attack, but due to the delicate location of the clot, major damage occurs at a quicker rate.

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Harper was unconscious for two days and in the hospital for more than a week. He found out afterward that he had a genetic cholesterol issue that put him at risk of a heart attack, which is why knowing your health history is a pillar of his latest healthy living campaign, “Survivors Have Heart.”

“You have to know your history, and you have to know what’s going on with you,” he said. “From the outside, I’m the picture of health. I’m the health and fitness guy doing everything right – it wasn’t until after the fact that I found out that I had this genetic issue.”

Harper modified his diet under his doctor’s direction and made the change from high-protein, high-fat to a more balanced variety. He said he favors more low-fat options now and reduced his red meat intake to about once a month, instead consuming more fish, chicken and eggs.

In the age of social media influences and brand marketing, Harper said a goal of his campaign is to provide easy-to-follow guidelines for his followers so that they don’t turn to misinformation or fall for products offering false promises.

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“All the tricks that are out there, they are tricks that people cannot sustain,” he said. “There’s so much white noise where there’s just a lot of misinformation and information that gets wrapped around a product that is trying to be sold. We all know what to do; you eat clean, you try to stay away from fast foods and processed foods and you go toward more wholesome-type foods.”

And while his former co-host Jillian Michaels has been vocal about her opposition to the popular Keto diet, Harper didn’t rule it out, instead, he focuses on the approach that no one diet fits all.

“If your doctor says it’s OK with you — then I’m fine with it,” he said. “If Keto is something that you can sustain and you are losing weight and your blood results are showing that your cholesterol is in a safe zone and triglycerides are good, then great. You’ve got to find a diet that really works for you.”

In addition to diet changes, Harper said he learned to let go of things out of his control and stress less.

“You get wrapped up in the news, you get wrapped up in the things in your life that you know what, it’s beyond your control, who cares,” he said. “Being able to say that to yourself — who cares, stop for a minute, breathe for a minute, manage that stress and don’t sweat the big things and don’t stress the small things. You don’t stress the things that are beyond your control.”

Part of Harper’s campaign includes traveling the country speaking to other heart attack survivors and giving them the opportunity to tell their story, which he said has been some of the proudest moments of his career.

“The whole campaign has been so personal to me,” he said.