Jon Hamm once admitted he wasn’t sure marriage was for him. Then he met Anna Osceola, got married and began openly talking about his hope of becoming a father.

Now, at 55, that hope is becoming a reality.

The “Mad Men” star and Osceola, 38, are expecting their first child together, PEOPLE confirmed. The news comes nearly three years after the couple married and follows years of Hamm speaking candidly about how his relationship with Osceola changed the way he viewed marriage, children and his future.

According to a source close to the couple, Hamm couldn’t be happier about becoming a first-time dad.

“Jon’s incredibly excited. This is something he and Anna have wanted and hoped for,” the source told PEOPLE. “He’s not thinking about his age or what anyone else has to say about it. He’s just really happy.”

The insider added that Hamm feels “happy, settled and ready” for fatherhood and considers himself fortunate to be starting a family with Osceola.

Hamm and Osceola first met in 2015 on the set of “Mad Men.” Hamm starred as advertising executive Don Draper throughout the acclaimed series, while Osceola appeared as receptionist Clementine in the show’s finale. They began dating in 2020 and became engaged in February 2023.

Four months later, they married at Anderson Canyon in Big Sur, California — the same location where the “Mad Men” finale was filmed. Their wedding included celebrity guests such as Paul Rudd, Tina Fey and Billy Crudup.

For Hamm, getting married represented a major change in how he once pictured his life.

His parents divorced when he was young, and Hamm has said that experience left him without a model of marriage that made him eager to pursue it himself.

“I didn’t look at marriage as a thing,” Hamm told The Hollywood Reporter in 2024. “Obviously, my parents were not married long, so I don’t have a model to look at and go, ‘Oh, this is how one finds happiness.’”

His relationship with Osceola changed that outlook.

“I just knew at a certain point I wanted to be with this person,” he said. Hamm admitted that proposing was initially frightening, but his feelings changed once the wedding day arrived.

“Everybody I love was there,” he recalled. “It was so emotional, and it felt right.”

Even before the couple married, Hamm was talking about how their relationship had opened his mind to a future he once hadn’t envisioned. During a 2022 appearance on “The Howard Stern Show,” he said he was thinking about “being married, having kids” and “defining a new version of happiness, life, wellness.”

By 2024, Hamm was openly hoping marriage would lead to fatherhood.

“I hope it turns into kids,” he said. “It’s not lost on me that I’m 53. I will be the old dad, but so it goes. It could be a good thing. We’ll see.”

Two years later, Hamm has his answer.

After a journey that changed his outlook on marriage and family, the actor is preparing for a role he once wasn’t sure would ever be part of his life: dad.