Standing out among the thousands of participants at The Straits Times Run in the City yesterday were a pair of "piggyback sisters" Melody and Merrily Tan.

In one of the most heartwarming scenes that came out of the event, 10-year-old Melody gave a piggyback ride to five-year-old Merrily. Both of them looked as happy as their names suggest.

When asked if she likes carrying her sister, the frank Primary 4 pupil of Tao Nan School said: "No. But she said she was tired and then she asked if we could carry her."

Carrying Merrily, who weighs 17kg, has become a responsibility that Melody and her mother Joycelyn Pang frequently shoulder out of love. Merrily is weakened by a rare incurable condition called Henoch- Schonlein purpura, an inflammation of the blood vessels.

Ms Pang, a single mother, said: "She's sick every month... She's got weak lungs and so she cannot exert herself too much."

Despite Merrily's condition, Ms Pang still takes her daughters out to participate in running events together. Thirty minutes into the 5km fun run yesterday, Melody had to carry Merrily. The family completed the route in 55 minutes.

Before yesterday's ST Run, their first, they had been to seven events, including the Pokemon Run in January and the Cold Storage Kids Run in May. Ms Pang intends to sign them up for 15 more events this year. The sales executive, 41, said: "I want them to share a common interest. In future, I hope they will continue to go for runs together, and when I am older, they will take me along for runs too.

"They look forward to it, especially getting the medal at the end."

While families enjoyed bonding during the ST Run, there were others who ran for different reasons.

Hong Konger Unique Chan, who is in Singapore to visit her boyfriend, celebrated a second lease of life after battling stage two lymphoma. Said the 21-year-old,who ran the 5km race: "The cancer made me realise that I might not get another second chance. So instead of spending time working all my life, I just thought I would do what I like - run."

While Ms Chan beat cancer, Ms Amy Chia, 50, overcame grief. Her husband of 21 years died of heart failure last April when he was 77. She had been his caregiver since he had a stroke in 2012. The widow was treated for depression due to the loss last year. As she recovered, she reinstated her routine - running at Chinese Garden six times a week.

Yesterday marked a milestone because she was finally able to take part in a running event. The financial consultant said: "It is a great personal accomplishment for me today because I'm able to let go of him now. I have conquered my grief."