Wu Yisen, an 81-year-old Hangzhou citizen, has been practicing winter swimming for over 20 years. Every time he went swimming, he would practice different swimming strokes, including breaststroke, backstroke, freestyle, and butterfly.

During the 20 years, Wu underwent two major surgeries on the gallbladder and stomach. But it didn't prevent him from swimming. "As long as I can still go out and walk, I will continue swimming," said Wu.