Rob Gronkowski will NOT be successful transitioning from the NFL to Hollywood if he doesn't take it seriously ... so says ex-NFL star Thomas Jones -- who says the move is hard as hell!!!
Of course, TJ knows first-hand what it takes to go from on-the-field stud to on-the-screen star ... he spent 12 years in the league before becoming a respected actor.
And, he tells us the only way Gronk is going to have similar success is if he truly devotes himself.
"Just commit yourself to the industry, man," Jones says of his advice to the future Hall of Fame tight end .