Mark Wahlberg's whole, practically-nude body needed a breath of fresh air in Miami Sunday.
The actor, who is in Florida shooting his upcoming flick Pain and Gain, gave passersby quite the show Saunday when he stood out in his hotel balcony in nothing but black briefs!
The married father of four, 40, has been strutting his stuff -- while shirtless -- all around Miami over the past month. His pumped-up appearance has channeled his days as rapper and Calvin Klein underwear model Marky Mark in the 90s. And despite speculation that the actor must be on some type of enhancement drugs, a source tells Us Weekly that his bulging biceps and sculpted pecs are a result of hard work, the old-fashioned way.
"Mark Wahlberg definitely is not using any kind of enhancements to pump up," the source told Us Friday. (Indeed, Wahlberg's rep tells Us that the star has never used steroids.)
Coincidentally, Pain and Gain is a 90s-era flick about two bodybuilders mixed up in an extortion and kidnapping plot.
"Even though the film is about steroid abusing gym rats, he took it as a personal challenge to get to the size he is at now and has been training non-stop," the insider explains, adding that the star has been using state-of-the art equipment on location.
His already-huge costar Dwayne "The Rock" Johnson just "inspire[s] him to work harder," the source adds.
This article originally appeared on Usmagazine.com: Mark Wahlberg Strips Down to Underwear on Hotel Balcony