DR OON CHIEW SENG, 100

At the grand old age of 100, Dr Oon Chiew Seng is still not done with work, and believes she has unfinished business.

After retiring as a gynaecologist at 75, she volunteered to set up Singapore's first home for dementia patients, called Apex Harmony Lodge, in Pasir Ris. Right up to her mid-90s, around the time she stepped down as its chairman, she was at the home every day, interacting with patients and being actively involved in its operations.

Dr Oon, who is sharp as a tack but a little hard of hearing, says: "After I stepped down from the home, I still felt I should, and can, do more."

She wanted to set up another small, non-profit nursing home and daycare facility for dementia patients, given the growing number of people diagnosed with the disease.

So she gathered a group of like-minded individuals, including two of her nephews, to help her fulfil her wish to do more for dementia patients.

To achieve this aim, she has donated millions - she declined to say how much exactly - to help set up the Dr Oon Chiew Seng Trust. The trust was registered as a charity in 2014. Dr Oon, who is not married, says: "One cannot take one's money to the grave, you know."

The youngest of 10 children of a businessman and a housewife, she was born in Penang in 1916 and worked as a nurse, even volunteering overtime when a typhoid epidemic broke out.

At a brother's insistence, she later went to medical school, but her training in Singapore was interrupted by the Japanese Occupation. She fled the war in a ship bound for Australia but ended up in India, as the ship changed course due to aerial bombing.

After the war, as a young doctor, she returned to Singapore and worked under gynaecologist and obstetrician Benjamin Sheares, who later became president of Singapore.

She specialised in obstetrics and gynaecology, performing up to 10 caesarean sections a day at the former Kandang Kerbau Hospital, where all the complicated births were sent to.

When Dr Oon, who describes herself as "assertive", could not see eye to eye with one of her bosses, she left the hospital to set up her own clinic in the 1950s - making her the first gynaecologist to go into private practice.

Her hobbies include keeping race horses, reading Agatha Christie novels and playing mahjong. Her mahjong friends included the late philanthropists Runme Shaw and Tan Chin Tuan ("Mr OCBC"), who would wait for her to continue the game if she had to leave to attend to a patient. She continues to play mahjong a few times a week.

After retirement, she travelled the world, even trekking her way up to the mountainous archaeological site Machu Picchu in Peru.

Besides travelling, Dr Oon, who gave up driving just nine years ago, decided to do "something meaningful" with her time.

When she was told of the need for a home for dementia patients, she went to Australia to learn about such nursing facilities. Apex Harmony Lodge opened in 1999, with 210 beds.

In the past, there were no purpose-built homes for dementia patients. Some were sent to the Institute of Mental Health, she says, despite their dislike for the place.

In recent years, she has given generously - she declined to say how much - to the National University of Singapore Yong Loo Lin School of Medicine, to fund research in areas such as women's health and ageing science.

And her trust, which aims to raise awareness about dementia and support caregivers, has funded an initiative to train service staff. This is to help people like bank and supermarket cashiers better serve customers suffering from dementia.

The board members of the trust are currently scouting for a location for a new home that she wants to build for dementia patients.

Those who know Dr Oon say she is a woman with a big heart, who gives quietly, dislikes drawing attention to herself, and treats all her patients - rich or poor - the same way.

Lawyer Josephine Choo, 45, one of the board members of the trust, says: "People are so amazed by her. She's so old, yet so sharp. She is also very giving, and very determined. If she wants it, she will try her best to get it done."

When asked why she is still thinking of helping others at her age, Dr Oon says: "Do you need a reason to help others?"

MS REBEKAH LIN, 31

While Dr Oon is, by far, the oldest philanthropist in Singapore, Miss Rebekah Lin, 31, is likely to be one of the youngest.

In 2013, she spearheaded the formation of the Jia Foundation, which is funded by her parents. Dad is Mr Andy Lim, founder of Tembusu Partners, a private equity investment firm. Her mother is former Cabinet minister Lim Hwee Hua.

Her parents have been giving for years to various causes, such as to the KK Women's and Children's Hospital Health Endowment Fund, which provides financial aid to poor women and children for their medical expenses. But Miss Lin says she felt they could do more if they started a foundation and funded causes in a way that was less ad-hoc and more long-term.

Miss Lin, the second of three children, runs the foundation. She says: "We want to focus on charities that do not get a lot of support, perhaps because I was also given many chances in life."

She says she was the only Raffles Girls' School student in her batch who could not make it to junior college. So she opted to go to the La Salle College of the Arts.

She dropped out a year later and decided to work as a chef. But she slipped at work, knocked over a pot of boiling water and suffered 12 per cent burns on her body.

That ended her dream of becoming a chef. After that, she took her A levels as a private candidate and got into the business school at Nanyang Technological University under a discretionary admission scheme to admit students on their other talents besides academic results. She says: "Both my parents went to Cambridge University but they never said I must go to Cambridge or the Ivy League schools. They gave me the freedom to choose, to find my way."

Today, Miss Lin, who is single, has found her stride and passion in philanthropic work.

The Jia Foundation (jia means family in Mandarin and refers to the wish to work with charities like a family) supports charities that do not get a lot of support, such as those that help people with mental illnesses and former prisoners. Among other things, it is also funding documentaries that help raise awareness about social issues and effect change.

Beyond giving grants, Miss Lin says she sees the foundation as being an enabler, linking up charities with other donors or resources.

She declines to say how much her parents have donated to set up the foundation or how much has been disbursed to charity.

But the amount would be at least $1 million, since the Jia Foundation is a charitable fund managed by private bank Credit Suisse's SymAsia Foundation - and the minimum sum to get such a fund started is $1 million. On the evolving philanthropic scene where the younger generation is running family foundations, she says: "We are now looking at the impact of the gift - to see how we can help you in the best possible way, instead of just giving you the money and walking away."