Eight hours into a 35-mile cycle across the Namib desert, Namibia, for Sport Relief in February, Nick Grimshaw developed severe heat exhaustion. A medical team put him into a car to shield him from the 44C (111F) temperature, and explained what was happening: he was at risk of organ failure. Grimshaw’s body started “vibrating”, as he puts it, and he began to panic. He needed a sedative injection to calm him down. The next morning, he had recovered, but sat out that day’s challenge.