After a 45-day fitness challenge, Mark Wahlberg is completely shredded

The 48-year-old actor is pushing his limits.

Mark Wahlberg is putting in the work -- in the gym and in the kitchen! The 48-year-old actor took to Instagram on Friday to share a shirtless photo of himself showing off his ripped bod. Wahlberg's six-pack abs and toned arms are on full display in the pic -- and he couldn't be prouder of his progress.

"F45 results 45 day challenge. @f45_training #ageisjustanumber #nowine54days #cleaneating," the father of four captioned the snap. Fans and celeb friends couldn't help but take notice. "We are looking for some skill players @markwahlberg," Tom Brady commented.