Stunning Welsh beauty Catherine Zeta-Jones is proving she’s still one of the toughest women in Hollywood.

As the Oscar winner filmed a scene for her new World War II drama, ‘Dad’s Army,’ in England in early November, she threw herself into her gritty role with gusto, shivering in the frigid ocean for nearly an hour.

“She still looked radiant and was chatting and laughing with members of the crew throughout the takes,” an onlooker tells ‘Closer.’

catherine zeta-jones
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Catherine and Michael in April 2013.

The role is just one more sign that she’s put the problems of the past two years – a temporary split with husband Michael Douglas, 70, two stints in rehab for treatment of bipolar disorder and Michael’s cancer scare – behind her.

"Almost all she has been known for [recently] has been her personal problems," says former entertainment producer Doug Ganley.

Related Story: Social Media Savvy: Catherine Zeta-Jones Joins Facebook & Instagram!

But with the focus on her career again, “I would call it a comeback.” And Catherine, 45, couldn’t be happier about closing the book on her private troubles.

“After such a hard couple of years, both Catherine and Michael feel like they are getting a fresh start,” an insider reveals.

To read the full story on Catherine pick up the new issue of 'Closer Weekly,' on newsstands now!