It ain't all just ice cream and lovey-dovey dates with Gisele for Tom Brady while on vacation in Italy ... he's clearly prepping for his NFL season as well -- hitting workouts on a yacht with no shirt on!
The Tampa Bay Buccaneers star was seen this week on a boat in Portofino getting in a serious sweat sesh ... sparring topless and also riding a stationary bike.
Tom threw the gloves on for several minutes -- working up a lather in the 85-degree Italian sun -- before finishing it all off with a ride.