Robert Downey Jr. is sober these days, but he says he will never forget his ugly struggle with drug and alcohol addiction.

"Not having done drugs for literally five or six years is a lifetime," he says in a candid interview in the November issue of Playboy. "I think of myself as someone who has no desire, use for or conscious memory of that life. And yet I don't shut the door on it, and I don't pretend it didn't happen."

He says he still has "very strong" recollections of his former self, whom he describes as a "messed-up kid ... lost, lost in narcotics."

Even today, Downey, 45, tells Playboy he feels like "a veteran of a war that is difficult to discuss with people who haven't been there."

And he doesn't take his sobriety for granted.

"Looking back, I think, 'Oh my God, I could have been done. I could have been so fried and so bad off and, oh my God, such a cautionary tale,'" he says. "And I still could be."

An integral part to staying clean: "You take responsibility, whether you're outraged by the results or not...." he says. People who think "'I'm a victim; I'm being victimized!" are "out of line."

Downey, who has a son, Indio, 17, and has been wed to producer Susan Levin for five years, also relies on self-discipline, which he says is "about respect. It's not even about self-respect; it's about respect for life and all it offers."

On the heels on Iron Man 2, Downey returns to the big screen next month in Due Date, a comedy by the director of The Hangover, which is already generating buzz.

"My age and my recent set of experiences ... have left me feeling I'm in the zone," says the actor. "This is just the sweet spot of my career and my life so far, and strangely, they've come at the same time."