Jamie will be running across Canada during part of their winter, so will encounter Arctic temperatures he has never experienced before.
We took him to Gloucerstershire University's Sport & Exercise Laboratory where they have a chamber in which the temperature can be lowered to minus 20C.
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The man behind multi-million pound 'The Black Farmer' sausage and meat brand has spoken to ITV News about his year long battle with cancer.
Chillier this evening with largely clear skies.
Mainly dry with sunny spells this afternoon.