Arnold Schwarzenegger wished his son, Joseph Baena, a happy 20th birthday the best way he knows how -- with a cute photo of them working out together.
The super buff duo flexed their muscles in a fun snap from the gym. Schwarzenegger captioned the photo with a heartfelt message:
"Happy birthday Joseph! You’re a fantastic son and a great training partner. You get stronger and smarter every year and I’m so proud of you. I love you."
The 70-year-old star regularly works out with Joseph, who shares some staggering resemblances to the former Mr. Olympia. Joseph is Arnold's son from his relationship with Mildred Baena. In 2011, news broke that Arnold had fathered a child 14 years prior with Baena, the family's housekeeper, while he was married to wife Maria Shriver.
Schwarzenegger has been spending a lot of time with Joseph since the initial news broke. Last year, Arnold celebrated Joseph's birthday by taking him to Oktoberfest in Munich, Germany.
It's been a big week of birthdays for Schwarzenegger. Last week the "Terminator" star wished his son, Christopher, a happy 20th birthday. Christopher is Schwarzenegger's youngest son from his marriage to Shriver.
Schwarzenegger shared an adorable throwback photo of his son as a toddler and captioned the picture, "Happy birthday Christopher! You're a wonderful student, a hilarious and kind soul, and a fantastic son. I'm so proud of you, I love you, and I can't wait to see what's next."
Happy birthdays to the whole Schwarzenegger clan!