Britain’s King Charles opened up about his cancer diagnosis on Wednesday, saying it can be a “daunting” and “at times frightening” experience for those living with the illness.

The British monarch said the “frightening” experience of cancer could also illuminate the “best of humanity” as he thanked medical workers and charities.

At a palace reception Wednesday, the king hosted representatives from cancer charities from around the UK and spoke about his deep and personal appreciation for their work.