• Kate Middleton has changed a lot, and many are impressed with what she has become before she turns 40
  • Middleton has remained a hands-on mom to her three kids while she takes on more workload as a working royal
  • Joan Black, who attended the duchess' Christmas carol concert, said Middleton appeared very confident at the event

Kate Middleton is embracing change as her birthday approaches.

The Duchess of Cambridge will turn 40 in January. An insider told People that Middleton is "flourishing" ahead of the milestone.

"She has really come into her own," the tipster added.

Middleton has been preparing for her role as the future queen consort alongside her husband, Prince William. She has been taking on more royal duties after the Queen canceled several of her engagements due to her recent health scare. Also, the Duke and Duchess of Cambridge had to step up and accept more workload after Prince Harry and Meghan Markle stepped back from their royal duties.

Just recently, Middleton hosted her first-ever Christmas carol concert at Westminster Abbey. The event was a tribute to the individuals and organizations across the U.K. who supported several communities amid the COVID-19 pandemic.

"Through our separation from others, we have been reminded just how powerful human connection is to us all. Just how much we need one another," Middleton wrote in the program for the concert. "And how loving and feeling a sense of belonging to one another can provide comfort in tough times. The importance of simply being together."

Joan Black, who attended the concert and was acknowledged for her work in helping the elderly during the lockdown, praised Middleton's statement.

"What she wrote was beautiful, and to bring everyone together like this is lovely. I felt she was really confident. We are doing well if that's our future Queen," she said.

Despite taking on more workload, Middleton has remained hands-on with her three children — Prince George, 8, Princess Charlotte, 6, and Prince Louis, 3. A family friend told the outlet that the duchess is "hugely involved in every single part of their day."

The source also praised Middleton for being "focused" and "professional." The duchess has become "more and more impressive as time goes on," the insider added.

Middleton, who has been a part of the firm for a decade, has changed a lot. An unnamed insider also spoke with Us Weekly's "Hot Hollywood" podcast in October and pointed out how much she has changed. The tipster said Middleton felt nervous around the Queen and was "desperate to impress" when she was still new. But she has grown to become one of the people the monarch trusts.

"Over time, Kate has proved to the queen that she can be trusted and they developed a great relationship," the insider said. "Kate has become a fearless public figure and knows protocols like the back of her hand, Elizabeth feels confident that Kate will make a great queen."

Kate Middleton
LONDON, UNITED KINGDOM - NOVEMBER 24: Britain's Catherine, Duchess of Cambridge speaks with Dr Elizabeth Rapa Senior Researcher from the University of Oxford, during a visit to Nower Hill High School on November 24, 2021 in London, England. During the visit the Duchess joined a science lesson studying neuroscience and the importance of early childhood development. Kirsty Wigglesworth-WPA Pool/Getty Images