King Charles III resumed his public duties on Tuesday with a visit to a cancer treatment center, where he met with patients and staff before heading to an appointment to be treated for his own illness.

During his appearance at the Macmillan Cancer Centre at University College Hospital in central London, Charles, a new patron of the charitable organization Cancer Research UK, shared that it was “a bit of a shock to be diagnosed with cancer.”

When a patient asked how he was, Charles answered, “Not too bad.”

During the visit, Charles looked thrilled to be back at work with Queen Camilla by his side. He gratefully accepted flowers and was keen to speak with patients as well as the center’s medical staff.

Sources close to the king say he is committed to raising awareness about cancer and early diagnosis following his and daughter-in-law Kate Middleton’s diagnoses last month. He personally chose to visit the cancer center as his first engagement after a few months taking only private meetings. While the palace has not confirmed the type of cancer the king is suffering from, he is undergoing treatment as an outpatient in central London and was on his way to an appointment after Tuesday morning’s engagement.

“We need to get more people tested early,” Charles said during his visit. Sources add that Charles is eager to use his own experience to highlight the importance of early detection. His cancer was an incidental discovery following a routine procedure for a benign prostate. During the procedure, tests revealed a different type of cancer was present.

Charles’s transparency about his condition resulted in a sizable increase in inquiries to NHS helplines, with many young men wanting to get screened.

During his visit, Charles saw a CT scanner that helped save 250 lives in the past two years by detecting the early stages of cancer. “The trouble is to get enough people early. There’s so much positive news,” he told Macmillan Cancer Centre staff.

As Vanity Fair previously reported, Charles is very optimistic about his treatment and prognosis and has been in good spirits throughout.

He is said to be “delighted” to be back on official engagements and looking forward to appearing at upcoming events including garden parties at Buckingham Palace and Royal Ascot. He is expected to attend the King’s Birthday Parade, Trooping the Colour in June.