People practice Taiji (Tai Chi) at Jiangbin Park in Mudanjiang, northeast China's Heilongjiang Province, Dec. 21, 2020. (Photo by Zhang Chunxiang/Xinhua)

A resident exercises at Jiangbin Park in Mudanjiang, northeast China's Heilongjiang Province, Dec. 21, 2020. (Photo by Zhang Chunxiang/Xinhua)

People practice Taiji (Tai Chi) at Jiangbin Park in Mudanjiang, northeast China's Heilongjiang Province, Dec. 21, 2020. (Photo by Zhang Chunxiang/Xinhua)

An enthusiast of winter swimming jumps into the water in Mudanjiang, northeast China's Heilongjiang Province, Dec. 21, 2020. (Photo by Zhang Chunxiang/Xinhua)

People skate on a natural ice rink in Mudanjiang, northeast China's Heilongjiang Province, Dec. 21, 2020. (Photo by Zhang Chunxiang/Xinhua)