The Hollywood heartthrob, 51, took to social media on Thursday, Dec. 22, to give his fans a little holiday gift in the form of a shirtless Instagram video.  In the steamy new clip, Wahlberg shows off his shredded body while flexing his muscles for the camera, as he promotes Performance Inspired Nutrition, a nutrition brand he co-founded for athletes and fitness enthusiasts.  “Getting ready for the Christmas holiday,” the Ted star is heard saying in the clip, while doing various poses and stretches in the mirror to showcase all of his bulging muscles.  “Go put in that work,” he then says to his followers, adding, “Inspired to be better,” from his brand’s motto.  The video then cuts to a clip of Wahlberg interacting with Tom Dowd, who co-founded the company along with the Uncharted actor.  Wahlberg then gives Dowd a swift punch to the gut, while joking, “We got a new [punching] bag.”  “Nobody was hurt making this video!!” Wahlberg assured in the caption of Thursday’s post.  “Damn brother great shape 🔥” one person commented under the video, while someone else chimed in, “Let’s go 🔥🔥🔥”  “Killin it my man!” fellow actor Mario Lopez added.