Joseph Baena is celebrating entering his late 20’s. The athlete and actor revealed that he spent his birthday participating in the Malibu Triathlon, showing off his hard work while in a Speedo. Arnold Schwarzenegger shares a hilarious post about subscribing to his newsletterJoseph Baena reveals how his father Arnold Schwarzenegger has impacted his fitnessA post shared by Joseph Baena (@joebaena)Baena shared his birthday post on Instagram, where he shared a clip of himself running out of the water, exhausted after completing the triathlon.