The soles of Hannah Cox's trainers tell their own story. Patched up with pieces of a car tyre and orange with dust, it's clear they have covered a lot more ground than just a solitary marathon. While some of the thousands of finishers of Sunday's London Marathon might be waking up barely able to get down the stairs, vowing 'never again', consider this - what if you now had another 26.2 miles to run? And then another, and another and another. For 100 consecutive days? Across India?