Josh Hartnett wasn’t prepared for the bombshell advice Matt Damon dropped ... old’ As Hartnett tells it, Damon’s general rule ...

Matt Damon's advice for Josh Hartnett while filming ... has a general rule when taking on roles: "Don't gain weight over 40." ...

Josh Hartnett has shared the “unhelpful” advice that Oscar-winner and co-star Matt Damon shared with him ... He told me not to gain the weight I’d already gained for the role.