"Age is just a number," Wahlberg said in the caption, prompting Mario Lopez congratulate him on repping guys in their forties: "Show em what fellas in their 40’s are all about! You look awesome bro!!"
Wahlberg took the photo after completing the F45 Challenge, an eight week fitness program which focuses on burning fat and building muscle through a combination of HIIT, circuit training and functional training. He's also been abstaining from alcohol, hence the "no wine 54 days" hashtag. Wahlberg is a fan of F45 workouts, and recently put his brother Donnie through his paces with some full-body F45 circuit training. (Spoiler alert: Donnie didn't love it quite so much.)
Of course, Wahlberg is no stranger to challenging himself: the 48-year-old actor went viral last year when he shared his workout schedule to Instagram while training ahead of filming The Six Billion Dollar Man. The intense regime started at 2:30 in the morning, and included two workouts every day followed by a recovery session in a cryotherapy chamber.
These days, he starts working out at 4 a.m. "I’m very precious with my time, which is why I’m so disciplined," he told us. "I try to inspire people that there is enough time in the day to accomplish all of your goals and find that great balance."
This article originally appeared on Men's health