SINGAPORE - Ultramarathoners Yong Yuen Cheng and Lim Nghee Huat are starting to feel tired after running 50km for seven days straight.
They have 43 more days of running in their attempt to complete 50km for 50 consecutive days to celebrate Singapore's 50th birthday.
"We'll carry on," said Mr Yong, a 43-year-old physical education teacher.
"One day at a time."
The runners are already starting to experience muscle aches in their calves, hamstrings and quadriceps from pounding the pavement for seven hours for a week.
Said ultramarathoner Gerrard Lin, 31, who has joined Mr Lim and Mr Yong for the last seven days: "It's pain everywhere, I'm barely making it but Mr Lim and Mr Yong are still going strong."
To recover, they go to bed at 9pm at night, ensuring they have enough rest before getting up at 5am for a 7am run the next day.
They hydrate themselves as they run and consume carbohydrate-rich foods such as prata and bread along the way. Sunburn has not been an issue, as members from the supply crew spray water on them to cool them down and they apply sunblock liberally.
The runners finished a 50km route around Upper Peirce Reservoir in seven hours and 11 minutes on Wednesday. They have been running the same route for the past three days as it is cool and shady, providing relief in Singapore's stifling heat.
Mr Lim also tripped and fell on a curb on Saturday. So a runner-friendly route with fewer kerbs and traffic lights would put less stress and help him recover, Mr Yong said.
The trio were accompanied by air steward Randall Kok, 36, an ultramarathoner, and Institute of Technical Education teacher Yi Wei, 27, as well as another runner Cheryl Ng, who happened to be running in the area.
Mid-way, they ran past a plaque indicating that Singapore's founding Prime Minister Lee Kuan Yew had opened the Upper Peirce Reservoir in 1977.
"I'm glad that Mr Lee made an effort to green Singapore," Mr Yong said.
"Without him, we would not have such lush surroundings to run in, or a beautiful garden city to live in."
Click here to read more stories about the Go50 Run and get regular updates on the runners' progress since Day 1.