Arnold Schwarzenegger's 'secret son' Joseph Baena is following in his father's bodybuilding footsteps.
The 23-year-old lovechild of Arnold, whose father had an affair with a housekeeper while married, let his fans in on the dramatic transformation is currently undergoing on Instagram.
Joseph showed off his sculpted torso and flexed his biceps for the camera after whipping off his shirt at the gym.
He then takes on an iconic bodybuilding pose by holding his wrist with one hand and flexing his bicep towards the camera.
In the clip, Joseph begins by wearing a tank top that emphasises his hulk-like body as he lifts a pair of 50lb bar bells.
Last month he posted a heartwarming photo of his father helping him train at an outdoor gym.
He admitted that Arnold doesn't let you 'cheat' when you train with him and is strict with his regime.
"You have to go all out and absolutely NO cheating when you train with him, so you know I’m going to be hurting tomorrow," Joseph said in the caption.
Before Schwarzenegger shot to fame as a movie star and politician, he was a champion bodybuilder in Austria, where he is from, and was hailed the Austrian Oak.
In 1970, at the young age of 23 - the same age as Joseph now - he became the youngest ever winner of the bodybuilding title Mr Olympia.
He retired from the sport a decade later.
He legally took steroids while he was young and in training and explained the experience years later when he was the Governor of California.
He doesn't endorse using steroids now, he admitted: "I have no regrets about it because at that time, it was something new that came on the market, and we went to the doctor and did it under doctors' supervision."
He continued that it was a "new thing" when he tried it.
The star previously opened up about how he was told he would never make it in the movie business because of his strong accent, which he is now known for.
Schwarzenegger and his estranged wife, Maria Shriver, share four children, Katherine, 31, Christina, 29, Patrick, 27 and Christopher, 23.
Maria was pregnant with Christopher while the family's housekeeper, Mildred Baena, was expecting Joseph.
Joseph is now taking on his first acting role, a sci-fi comedy called The Chariot, mirroring Arnold's sensational showbiz career.