He makes people laugh for a living, but behind closed doors, David Letterman** struggled to maintain that happy, gap-toothed grin.

Speaking to Charlie Rose on CBS' This Morning, the Late Night veteran, 65, opens up about his long battle with serious depression and his reluctance to get help -- particularly of the pharmaceutical kind.

Admitting he was "always skeptical" about taking depression medication, Letterman worried "it would make me loopy or make me hallucinate or make me drowsy."

But then, Letterman came down with the shingles. "Part of the concoction of drugs they give you to fight that pain are pretty serious, and I just got tired of taking them," says the CBS star, who quit the pain drugs "cold turkey." That decision led Letterman to develop "nervous anxiety" on top of his depression.

"Then I was really screwed," he recalled -- finally turning to his friend and doctor, Louis Aronne, for help.

"So that's when I said to Louis, 'OK, OK, I'll try anything just to get rid of this depression.'" he explained. "Because it's different than, 'Oh, I don't feel good today.' It's different than feeling sad. It's different than feeling blue. It's really, like a friend of mine says, it's the world with 20/20 vision."

Letterman has much to be happy about these days, too: He married girlfriend Regina Lasko in 2009, and they are a son Harry, 9.

He initialy balked at fatherhood long before Harry was conceived.

"I just thought…I can't do both," he said. "I can't try to have a successful television show and be a father. And I was wrong about that, because as difficult as being a father is, it's entirely complementary with everything else in your life."

This article originally appeared on Usmagazine.com: David Letterman Opens Up About Depression, Anxiety Battle