Arnold Schwarzenegger celebrates his birthday in the gym with son Joseph Baena

Happy birthday Arnold Schwarzenegger!

Although the "Terminator" actor just turned 72-years-old, he's never looked better. Joseph Baena took to Instagram on Tuesday to celebrate his dad, sharing a photo of them training at Gold's Gym- the famous location where Schwarzenegger spent most of his time during his high-profile bodybuilding career.

"BIG happy birthday to the best training partner in the world! Love you dad,” the 21-year-old wrote alongside the photo.

Fans gushed in the comments section praising the former politician. "You are so lucky to be his son. He has been my idol since I was a small boy. He is the reason I wanted to start working out," one person wrote.

SEE ALSO: Arnold Schwarzenegger's look-alike son, Joseph Baena, recreates iconic pose

Patrick Schwarzenegger also honored his dad, sharing a photo with his siblings, Christina, Christopher and Katherine, whom Arnold shares with ex-wife Maria Shriver. The Instagram showcases a hilarious cake with a photo of Arnold in a hot tub smoking a cigar, clearly living his best life.