Ben Affleck in the Director's Chair

Ben Affleck has traded his Boston Red Sox baseball cap for a director's hat, at least for a little while.

The famous actor and Academy Award-winning writer is making his feature-film directing debut with "Gone Baby Gone," and critics are saying he may have found his calling.

"Gone Baby Gone" is part thriller, part detective story, but all full of surprises.

With his directorial debut, Affleck is joining the ranks of actor-turned-directors Clint Eastwood and Robert Redford and he says it hasn't been an easy road. Directing has become more than a hobby, it has become his obsession.

"This was, you know, completely all-consuming, every day, all day, going to sleep, thinking about it until you fall asleep," he told Diane Sawyer on today's "Good Morning America."

Affleck added that he became so consumed by the project that at one point he was hospitalized for a stress-induced migraine.

"Once I figured out and got the medications, I was able to get it under control," he told Sawyer.

The stress may prove to be worth it in the end, as critics are heralding his first efforts.

"It's definitely something I hope to be able to do forever, as long as I have the opportunity," Affleck said, adding that he would like to continue to act, too.

Affleck said initially, he was developing the movie as a vehicle to star in himself.

"As I got more interested in the idea of A.) directing, and, B.) the idea of — the script itself became kind of more interesting — I thought, maybe I'll direct it myself and I won't act in it. I changed the part to the younger role and thought it made the story better," he said.

His younger brother Casey was eventually cast in the lead role.

"I knew his agent very well," Affleck said jokingly, explaining his brother was an easy catch.

In addition to his younger brother, the movie stars actor Morgan Freeman — an entirely different challenge where directing is concerned.

Affleck said directing Freeman involved less direction and more respect.

"When you have Morgan Freeman, you don't need very many takes. Directing a great performance out of Morgan Freeman mostly involves saying 'action,'" Affleck said.

Affleck also turned to real people, for authenticity's sake.

"The idea for me was to make this as authentic a feeling movie as possible. I wanted people to feel as though they really were in this neighborhood in these bars, in these people's houses," he said.

So far, the feeling his film is generating in critics and audiences alike is a good deal of Oscar buzz.