Just a year ago, Kate, 43, had taken part in the same ceremony while undergoing chemotherapy for an undisclosed form of cancer, her role more limited as she focused on healing. This time, she was present at every turn, including a significant appearance on the parade ground alongside King Charles, 76, and Queen Camilla, 77, fulfilling her role as honorary Colonel of the Irish Guards.

“She projected the confidence of someone who has enthusiastically reconnected with her public duties,” royal biographer Sally Bedell Smith tells PEOPLE in this week’s issue.

After an intensely challenging year — one that brought a devastating diagnosis and relentless speculation about her health even before she had the chance to tell her and Prince William’s children — Prince George, 11, Princess Charlotte, 10, and Prince Louis, 7 — Kate is focused on the road ahead.

“She has not been able to have the privacy that a person who faces this kind of illness is normally afforded,” says a source close to the royal household.

“She gets so much sustenance in nature, and she’s lucky to have homes in some of the most beautiful parts of Britain: in Norfolk and on the Windsor estate,” says Queen Elizabeth’s former spokeswoman Ailsa Anderson. “She’ll be able to reenergize herself.”

As Kate and William emerge from their most difficult chapter, the princess is carefully pacing herself. “She’s being sensible, listening to what her body is telling her and easing back into public life,” Anderson says.

Still, challenges loom. The shadow of King Charles’s cancer diagnosis, which aides now describe as a “managed” condition, means that Kate, William and their inner circle are preparing for an inevitable transition.

“There are some major shifts coming behind the scenes,” a friend tells PEOPLE. With their future roles as King and Queen drawing closer, the couple are focused on building a trusted team of top advisers. “They are really finessing what works and what doesn’t,” the friend adds.

But Kate, like William, is ready for what lies ahead. Bedell Smith, who has written extensively about Charles and the late Queen Elizabeth, recalls a saying from Elizabeth’s mother, the Queen Mother: that the position of monarch — and of their consort — is “a vocation, not a role.” It’s a fitting description for Kate, who in recent years has embraced her duties with a new level of professionalism and purpose.

Kate has also shown profound solidarity with families facing cancer, sharing parts of her own journey with those going through similar battles. Last October, she and William gave teen photographer Liz Hatton — who was diagnosed with a rare and aggressive abdominal sarcoma called desmoplastic small round cell tumor — the chance to fulfill a bucket-list dream by photographing an event at Windsor Castle.

Since Liz’s death at 17 in November, Kate has remained a steadfast support for her family. “It shows that cancer can touch any of us,” says Liz’s mother, Vicky Robayna, reflecting on Kate’s diagnosis and the deep connection the princess formed with her family, especially her 9-year-old son Mateo. “It felt like walking into an extended family and having arms wrapped around you.”