Forget the TB12 Method ... Rob Gronkowski clearly needs to come out with his own fitness line -- 'cause Camille Kostek says he's the reason for her smokin' hot bod!!
The Sports Illustrated Swimsuit model -- who joined Harvey and Charles on "TMZ Live" -- says she's been training with the Patriots tight end ... and credits his workouts for gettin' her magazine ready this fall.
"I'm doing the same workouts [as him]," Camille says ... "Maybe not the same weight, but I'll do just as many reps and he'll push me until I can't go anymore.