Miami just got a little hotter -- Mark Wahlberg is in town shooting a movie and yes, he looks good.

The 40-year-old looked fit and fine when spotted on set of his upcoming flick "Pain and Gain" on Monday. Dressed in a white tank top and white-and-blue striped track pants, the father of four was seen doing crunches from a sit-up bar attached to the wall of a building.

"Pain and Gain" follows the story of two Florida bodybuilders -- Mark and Dwayne "The Rock" Johnson -- who get caught up in an extortion ring and kidnapping scheme. Ed Harris, Tony Shalhoub and Anthony Mackie also star in the film, scheduled to hit theaters next year.

Click "Launch Gallery" below for shots of Mark keeping fit on set in Miami!

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