If he is in chronic pain it suggests his going on a physically challenging reality TV show isn’t the best idea on the part of himself, his staff or ITV management
Presumably challenge one is “don’t lose an election to a dolphin”
https://www.theguardian.com/politics/2023/nov/18/nigel-farage-says-he-may-not-be-able-to-do-some-im-a-celebrity-challenges?CMP=Share_iOSApp_Other