Andrew Murray aims to run seven ultra marathons on seven continents in a week to raise cash for the Scottish Association for Mental Health charity (SAMH).
The Edinburgh GP, 32, originally from Aberdeen, will run across some of the world's most hostile environments – glaciers, deserts and mountains –over the coming days.
The Scottish Government's fitness czar has just won his first event in the Antarctic in a time of three hours and 41 minutes.
Dr Murray, who recently took up running, beat stiff competition when he took on some of the best marathon runners from around the world.
The ninth Antarctic Ice Marathon took place in freezing conditions at the foot of the Ellsworth Mountains near the South Pole on Wednesday.
They are the highest mountain ranges in Antarctica, forming a 224-mile long and 30-mile wide chain of mountains on the western margin of the Ronne Ice Shelf.
A spokeswoman for the GP said: "Andrew Murray kicked off his seven marathons, over seven continents over seven days yesterday by competing in the Ice Marathon in Antarctic. Running in the freezing cold, Andrew did what he does best and charged through and ended up winning the Ice Marathon, coming first with an unbelievable time of 3:41.15 hours."
Dr Murray, who is orginally from Aberdeen, was recently recruited by the Scottish Government to highlight the importance of physical activity.
His challenge will now take him to Patagonia, Atlanta, London, Egypt, Dubai and Australia. Dr Murray aims to promote health and raise more than £10,000 for the Scottish Association for Mental Health charity.
Last year he ran 2659 miles – averaging more than 34 miles a day – from Scotland to the Sahara in 77 days.