Robin Williams’s life is the center of a new HBO documentary. The movie looks at the renowned comedian’s struggles and triumphs over his battle with depression — which eventually lead to him taking his own life in 2014.

At one point in the trailer, Robin is asked if he suffered from a childhood fear of abandonment. “Yeah, it’s a primal fear for any child and it dictates a lot of how you deal with life.”

“Every person is driven by some deep secret,” he added in the trailer. “There was fear sometimes to run away from it all, sometimes to run into it all.”

His son Zachary said, “My father didn’t always feel he was succeeding, but he was the most successful person I know.”