Arnold Schwarzenegger’s son Joseph Baena celebrates his 26th birthday with a video of him in Speedos on the beach

Arnold Schwarzenegger’s son Joseph Baena celebrates his 26th birthday with a video of him in Speedos on the beach

Arnold Schwarzenegger’s son Joseph Baena celebrated his 26th birthday with a sweet video shared to Instagram.

The fitness enthusiast – whose half-brother Christopher Schwarzenegger also just turned 26 – celebrated his special day by hitting the beach in a Speedo.

The muscular actor wore nothing but a pair of tiny black briefs as he took a dip in the ocean before running through the sand.

The star’s rippled abs and chiseled arms were on full display in the second-long clip posted to his 539,000 followers.

He wrote in the caption, “Twenty-six? More like Twenty SICK! Here’s your POV of me in my late twenties, with a crying laughing emoji.

Beach birthday! Arnold Schwarzenegger’s son Joseph Baena celebrated his 26th birthday with a sweet video shared to Instagram

Less is more: The fitness enthusiast – whose half-brother Christopher Schwarzenegger also just turned 26 – celebrated his special day by hitting the beach in a Speedo

Less is more: The fitness enthusiast – whose half-brother Christopher Schwarzenegger also just turned 26 – celebrated his special day by hitting the beach in a Speedo

The post quickly racked up thousands of likes from Baena’s digital fanbase.

Despite the cloudy day, the gym rat was all smiles as he took part in a fitness circuit with others.

On one of his muscular biceps the number 743 was written in black marker, indicating his status in the event.

He also wore a red ankle bracelet as he sprinted through a large, red finish arc with others.

Later in the day, the multihyphenate took to his Instagram Stories to share a gym selfie.

He was wearing a faded black T-shirt, black athletic pants, long white socks and a pair of brown and white checked Vans sneakers.

Posing in a full-length mirror, he smiled with his mouth closed and wrote “BDay pump,” with a green check mark emoji.

The messages come a day after the veteran DJ said he had completed his first triathlon.

Wow: The muscular actor wore nothing but a pair of tiny black panties as he took a dip in the ocean before running through the sand

Wow: The muscular actor wore nothing but a pair of tiny black panties as he took a dip in the ocean before running through the sand

Excited: He wrote in the caption, “Twenty-six?  More like Twenty SICK!  Here's your POV of me in my late twenties, with a crying laughing emoji

Excited: He wrote in the caption, “Twenty-six? More like Twenty SICK! Here’s your POV of me in my late twenties, with a crying laughing emoji

Routine: Later in the day, the multihyphenate took to his Instagram Stories to share a selfie at the gym

Routine: Later in the day, the multihyphenate took to his Instagram Stories to share a selfie at the gym

Following in his father's footsteps: Arnold's son Joseph Baena, like his father, started bodybuilding and acting

Following in his father’s footsteps: Arnold’s son Joseph Baena, like his father, started bodybuilding and acting

He uploaded a smiling photo of himself standing on the beach and flexing one of his impressively sculpted arms.

In a pleased caption he wrote: ‘Today I participated in my first triathlon! What an amazing experience it was to compete against such great athletes.

‘With my birthday approaching, I wanted to challenge myself in a new way. I feel like I did really well and I’m proud of myself for going this far. I really believe that if you have muscles, you should be able to use them!’

Joseph is Schwarzenegger’s love child, born after the actor had an affair with housekeeper Mildred Patricia Baena. Like his father, he is into bodybuilding and acting.