The fitness symbol among the Yangtze swimmers

The clock had yet to strike 6 am when 53-year-old Zhu Biwu stepped out from the comfort of his home in Wuhan, Hubei province, on a frigid morning in March.

Like most "early birds" of his age, the labor union chairman was heading to his office, which is located across the Yangtze River that runs through the city. However, he was taking a route unlike anyone else.

With two bright orange waterproof floatation bags attached to his waist to alert ferries on the Yangtze and to store his belongings, the Wuhan native has been swimming over 2 kilometers to work most days over the last decade, except on the coldest days in January and February.