Val Kilmer, one of the most popular Hollywood actors of the 1980s, spoke at the NOVUS Summit on sustainable development at the United Nations in New York earlier this month in order to deliver a presentation on his work in promoting media and arts literacy.

The 59-year-old, who has been suffering from throat cancer, struggled to speak while discussing his work with his TwainMania Foundation. Kilmer also received an award for his humanitarian work with the organization. The NOVUS Summit’s main objective is to attain a series of global sustainability goals by 2020.

WATCH: VAL KILMER ACCEPTS AWARD AT UN NOVUS SUMMIT

Kilmer, who starred alongside Tom Cruise in 1986’s Top Gun, is set to reprise his role in the sequel, Top Gun: Mavericknext year.