Kate Middleton displays 'strength' after attending Trooping the Colour ceremony despite cancer treatment

LONDON, ENGLAND: Princess of Wales, Kate Middleton continues to make an effort to get out and attend events despite her cancer diagnosis.

However, a source revealed that the Princess of Wales was "exhausted" following Trooping the Colour on June 15, her first public appearance since receiving a cancer diagnosis earlier this year.

Kate Middleton's 'display of strength proves she’ll make worthy queen one day'

Despite receiving cancer treatment in May, Kate was present at Trooping the Colour on June 15, King Charles' ceremonial birthday.

Despite looking stunning at the event, an insider revealed that the Princess of Wales, 42, was worn out afterward, per OK! Magazine.

The source said, "Kate was exhausted afterward. It was a long day, and it took a lot out of her."

Referring to Kate's extensive Instagram post that described her struggle with health, the insider said, "That’s why she wrote that June post."

The insider added, "She absolutely has bad days, and that’s something she wouldn’t have shared in the past. Kate’s not the only person battling cancer, and she realizes that being truthful about her struggle will help others."

Thus far, Kate has not committed to any forthcoming events because she is "learning how to be patient" during this trying time.

Though she's optimistic about attending "a few engagements" during the summer, Kate acknowledged that she's "not out of the woods yet."

The source praised the princess and said, "Her display of strength proves she’ll make a worthy queen one day. She’s a fighter, for herself, her family and her country."

Prince William reportedly 'very proud of Kate Middleton' following her public appearance

Kate's joyful smile during King Charles III's formal birthday celebration suggested that her day of public return was a success.

Despite being "exhausted" after the event, the source revealed that Prince William was "very proud of Kate Middleton."

The source close to the royal family revealed to Life and Style, "Kate was nervous making her reappearance. She worried she would look tired or too thin at the parade, but she looked amazing."

"The supportive response Kate got boosted her confidence, and it was apparent."

With the elegance and grace that have won her such a following, Kate wanted to prove to the world that she did not give up. The insider added, "Prince William was very proud of her and so were the rest of the royal family."

However, Kate—who has been spending most of her time relaxing at Anmer Hall in Norfolk with William, 42, and his children, Prince George, 10, Princess Charlotte, 9, and Prince Louis, 6—did not find the outing to be easy.