Tarek El Moussa has proved his estranged wife and Flip or Flop co-star, Christina El Moussa, isn't the only one in their relationship who has achieved a killer revenge body.

On Thursday, Tarek, 35, posted a shirtless photo of himself on Instagram in which he's lifting heavy weights and showing off his extremely buff, chiseled physique.

"I shot this and was too embarrassed to share so I didn't... I know my journey has inspired many people so I made the difficult decision to post.. this is after battling 2 cancers and a debilitating back injury," Tarek captioned the jaw-dropping photo.

"My doctor said 'You would probably never be able to lift weights again'... that motivated me to prove him wrong and get into the best shape of my life!!! Thank you to my trainer @quintin_tucker for all the hard work and motivation and @pyejirsa for the amazing photos. Remember....it's not the size of the dog in the fight, it's the size of the fight in the dog."

Tarek's trainer, Quintin Tucker, is now revealing what the process was like to get the HGTV house flipper into the best shape of his life.

At first, Tarek went looking for a physical/corrective therapist after his back surgery.

"When I first met Tarek he could hardly walk. He had reached out to a friend of mine to find someone who could help him get back on his feet and get back into the best shape of his life," Quintin told E! News.

"It is my understanding that Tarek, after meeting with many specialists, was told he would never be able to lift weights again, and all that could be expected was to manage the pain he was in. When I started working with him he was in a tortuous amount of pain and had been on a multitude of powerful pain medications."

Quintin, who also works as a sports performance and fitness trainer, confessed, "I was afraid I would break him. I could feel every one of his bones right under the skin and he felt extremely frail."

However, Tarek progressed drastically over the course of several weeks.

"After only two weeks we had him off of all of his pain medication and began to lift weights. The amount of motivation and fight Tarek had in the beginning is unmatched by any other client I have yet had and was paramount to his recovery. Session after session he would always say, 'I'm going to be your biggest transformation, I'm going to get back into the best shape of my life,' and he did," Quintin revealed.

Tarek apparently transformed his mind, body and soul during this journey, as the trainer said the reality TV star "has definitely changed as a man since we began lifting."
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"He came to me in possibly the lowest point he had yet experienced in his life. His body was broken, and after every battle he won, he was hit with another tragedy, cancer, back surgery, cancer again etc., until he could barely move without extreme pain and could definitely not even bend over at all," Quintin told E! News.

"I have seen Tarek transform from a very sad and weathered version of himself to the strongest and happiest version of himself I have seen to date."

Quintin also shared the fitness and nutrition secrets behind Tarek's apparent success.

Workout sessions reportedly last about an hour and the pair focus on mainly "multi-joint compound lifts, typically in supersets." Cardio is done on Tarek's own time but they have to adjust each training session depending on Tarek's body "needs" that day, which could mean heavier weights, higher intensity or higher volume.

As for Tarek's diet, Quintin said he consumes a "moderate amount" of protein and some healthy fats, plus intermittent fasting.

"As much as I would like to take credit, Tarek is extremely self motivated," Quintin gushed to the website.

"His biggest motivation was being told repeatedly that he would never be healthy again let alone lift weights. He just kept on saying, 'I am going to get in the best shape of my life.' It was his mantra and he believed it beyond a shadow of a doubt. I firmly believe this was magic behind his recovery."

In getting to know Tarek, Quintin said he was always impressed by how much of a family man he showed himself to be.

"I would drive up to his house and would wait for him in his gym while he woke up and we would work out before Taylor was awake," Quintin recalled.

"Occasionally she would wake up and run into the gym and begin lifting her mother's little three pound weights. It was the cutest thing ever. They would always hug and she would say, 'You're my best friend dad.' I always respected what a great father Tarek was, above all else."

Tarek filed for divorce from Christina in early January, one month after the couple publicly announced their split. They share six-year-old daughter Taylor and 19-month-old Brayden.

In recent weeks, Christina has been showing off her stunning, fit and toned body via bikini pictures as well as glamorous photo shoots she claims are outside of her comfort zone.