This story was first published on May 20, 2017, and updated on July 17, 2017
Madam Teo Yoke Lan works up to 11 hours daily, taking food to office workers in Tanjong Pagar and Raffles Place as an UberEats "walker". She is 70 years old.
Having made more than 300 deliveries over the last four months, she said she likes the job because the hours are flexible and she essentially gets paid to exercise.
But she is far from alone when it comes to elderly people who defy society's expectations of what they can do.
Here are eight others who remain active well into their golden years.
1. Makeup tips and YouTube videos from 'Grandma's Diary'
South Korea's Park Mak Rye, a sprightly 70-year-old, has more than 277,000 subscribers on her YouTube channel.
On it, she dispenses advice on applying makeup so as to resemble Amy Winehouse, among others, and trying out new activities - spiced with a dash of humour.
Her most popular video, in which she dons black eyeliner and red lipstick, has drawn more than 1.8 million views.
2. The 101-year-old gold medallist runner
Ms Man Kaur won the 100m sprint at the World Masters Games held in Auckland, New Zealand, on April 24. Never mind that she was the only competitor in the 100-and-over age category.
The "miracle from Chandigarh", as New Zealand's media dubbed her, completed the dash in 1min 14sec. She was introduced to running by her son Gurdev Singh, 79. She was 93 at the time, and in the years since has racked up more than 20 medals in various international competitions, reported The Washington Post.
This haul includes winning the javelin and shot put in the American Masters games last summer.
Ms Kaur, who lives with her son in Canada and spends time in India, aims to compete in next year's World Masters Games in Malaysia, according to The Indian Express.
3. Swinging and leaping on the parallel bars at 92
She started competitive gymnastics in her native East Germany when she was 10, but World War II, marriage and children put a stop to that.
Then Ms Johanna Quaas' quiet life changed in 1982 when, at 57, she met two old friends who were gymnasts. The trio decided to try training and competing professionally again.
Even though the two friends - one of whom was four years younger than Ms Quaas and the other five years older - have died, she continues to persevere in the quest.
The 2013 Guinness Book of Records recorded her as the oldest gymnast in the world, and she was also included in the International Gymnastics Hall of Fame.
4. Don't pick a fight with 'Gongfu Granny'
She may be 94, but Madam Zhang Hexian protects local villagers and fights local bullies in her hometown of Ninghai county, in eastern China's Zhejiang province.
She began learning gongfu from her father at the age of four, and, as reported by China's official Xinhua news agency earlier this year, she became a social media sensation when pictures and videos of her practising gongfu went viral.
Her son Feng Chuanyin said that she continues to wake up at 5am daily to practise martial arts moves.
Madam Zhang is now passing her gongfu skills on to the next generations - her grandchildren and great grandchildren.
5. Making fried dumplings by day, dropping techno beats by night
Deep in the underground clubbing scene of Tokyo, Ms Sumiko Iwamuro gets the crowd going at a time when you would expect your own grandparents to be in bed.
The 82-year-old, who goes by the moniker "DJ Sumirock", is Japan's first octogenarian disc jockey, according to The Times.
When she was in her 70s, she spent a year taking classes at a DJ school, Al-Jazeera reported. She was also introduced to the clubbing scene by a French event producer.
In the day, she still makes fried dumplings at a Chinese restaurant which she and her brother inherited from their father.
6. 'China's hottest grandpa' who models and acts
He may be 80 years old, but he has a body that could put many of those half his age to shame.
Mr Wang Deshun trotted topless down the Beijing catwalk in 2015, a one-off affair that captured the imagination of the Chinese Internet and launched him to fame, earning him the moniker "China's hottest grandpa".
He did it as a favour for a former student who was at the time working with Chinese designer Hu Sheguang.
Mr Wang spends two hours daily in the gym and pool, and last year acted in more than 10 television dramas and movies, primarily in supporting roles.
7. Party like these Russian grandmothers
This item is technically six people, but we hope you'll forgive that.
Russia's entry to the 2012 Eurovision song contest just missed the top prize.
But despite coming in second place, it won the hearts of millions.
Buranovskiye Babushki, or "Buranovo Grannies" in Russian, comprised six members whose oldest was at the time 74, and the youngest was 43, reported Time Magazine.
Their song was sung in their native Udmurt language, though the chorus comes in English, simple and catchy enough for anybody to follow:
"Party for everybody, dance
Come on and dance
Come on and dance
Come on and boom, boom"
8. India's toothless and jovial answer to Gordon Ramsay
She has recently cooked up a storm on social media.
If you have not yet heard of her, take time to watch how she cooks chicken - in a watermelon.
Madam Mastanamma, 106, comes from a remote village in Andhra Pradesh, and is the star of a YouTube cooking channel called Country Foods.
It is managed by her great-grandson Laxman Karre and his friend Srinath Reddy.
NDTV reported that the channel was initially started for bachelors, featuring simple foods that could be easily whipped up, but it did not receive much attention until Madam Mastanamma came into the picture.
The most popular videos now have millions of hits each. Oh, and does anybody want to learn how to cook an emu egg?
