Charles' speech highlighted the efforts of health care workers.

LONDON -- King Charles III spoke about the "uncertainties and anxieties of illness" as he delivered his annual holiday message from a former hospital chapel, a poignant location given the king's ongoing cancer treatment.

British monarchs typically deliver their annual holiday speech from a palace or castle. But Charles broke with the long-standing tradition to deliver his address - infused with personal vulnerability -- at Fitzrovia Chapel, now a community venue in central London.