Bob Harper, personal trainer and host of NBC's The Biggest Loser, says he's thankful to be alive after suffering a massive heart attack in February.

The 51-year-old Harper appeared Tuesday on NBC's Today show.

“I had what they call a widowmaker,” he said. “The fact there were doctors in the gym when I had the attack saved my life.”

“I was in full cardiac arrest. I was dead, on the ground dead,” said Harper, the author of three books on fitness.

When he woke up from a coma two days later, Harper said he didn't remember much about what had happened.

“I was like Dory from Finding Nemo with short-term memory, reliving the heart attack over and over,” he said.

Harper, who has a family history of heart disease, added that “genetics does play a part in this.”

Harper came out publicly on an episode of The Biggest Loser in 2013.