In a rare moment, viewers saw a vulnerable side of actor Robert De Niro when he was overcome with emotion during an interview on Katie Couric. He appeared with his fellow Silver Linings Playbook co-star Bradley Cooper and director David O Russell to talk about the issue of bi-polar and mental illness, which is dealt with in the movie.

When Katie asked Robert if he felt a larger share of responsibility doing a project that Russell was personally vested in, things got emotional.

Holding back tears, Robert replied “oh of course, I understand what he…I don’t like to get emotional, but I know exactly what he goes through.”

Robert felt a connection with the movie because his late father suffered from bi-polar disorder and bouts of paralyzing depression. Also, Bradley Cooper’s character in the film was inspired by Russell’s own son who suffers from a mood disorder, so the role really hit home for Robert.

Listen to a clip from the emotional interview in the Entertainment Report below.

Watch the full interview on Katie or jump to the 5:05 mark to see Robert De Niro’s heartfelt moment.