Actor Mark Ruffalo says compassion for people drew him to the lead role in director Ryan Murphy's film adaptation of Larry Kramer's Tony-winning play The Normal Heart.

In the upcoming HBO film, Ruffalo tackles his first gay role playing Ned Weeks, the hero of Kramer's play about the early days of the AIDS pandemic in New York City.

“I love people,” Ruffalo said in response to HuffPost Live host Alyona Minkovski's inquiry about his reasons for taking the part. “And I have a lot of compassion for the struggle of people. I was growing up during the AIDS epidemic, and I saw how cruel and how insensitive people were to these people suffering. It sort of has been forgotten in our culture what happened during those times.”

Ruffalo added that pioneering HIV/AIDS activists “brought us to the point today … gay marriage is as common almost as marriage right now.”

“That was an important story that needed to be told. And I was honored to tell it with the folks that I got to tell it with, and having Larry Kramer's words to convey it,” Ruffalo said. (The video is embedded on this page. Visit our video library for more videos.)

The film's all-star cast includes Matt Bomer, Taylor Kitsch, Jim Parsons and Julia Roberts.

(Related: Matt Bomer reveals he and Simon Halls married in 2011.)