Bob Harper goes back to 'square one' on treadmill after heart attack

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/ Source: TODAY
By Ree Hines

Bob Harper isn't letting a heart attack keep him down.

While "The Biggest Loser" trainer isn't back to calling the shots in the gym just yet, he is back on a treadmill and vowing to be "the best student" as he recovers.

Harper suffered a serious heart attack on Feb. 12, and since then, he's updated his fans every step of the way on Instagram — including a new video showing him taking a stress test.

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Alicia Keys' 2012 hit "Girl on Fire" scores the brief clip as Harper holds on to a handrail and goes for a walk, all while a doctor monitors his progress.

This subtle workout is a big change of pace for the fitness guru who usually prefers the high-intensity interval training of CrossFit routines.

RELATED: 'The Biggest Loser' trainer Bob Harper shares his powerful mantra

"Well while all of my @crossfit family is getting ready for 17.3, I'm walking on a treadmill doing a stress test," he captioned the clip. "Talk about starting back at SQUARE ONE. I plan on being the BEST STUDENT."

We apologize, this video has expired.

But this treadmill stroll isn't Harper's only workout.

RELATED: Bob Harper updates fans on condition following heart attack

He recently expressed disappointment about not being able to participant in the CrossFit Open competition but explained that he had his own trainer keeping him moving in meantime — his furry friend, Karl.

Karl still needs his daily walk no matter what, and Harper considers his dog his "best medicine."