At age 65, Dr Ang Yong Guan - the Progress Singapore Party's (PSP) candidate for the new Marymount SMC - has already run 10 marathons in his lifetime.
He is also approaching his 10th year in politics.
The psychiatrist and former army colonel stood as a Singapore Democratic Party (SDP) candidate in Holland-Bukit Timah GRC in 2011, and in Tanjong Pagar GRC in 2015 with the now defunct Singaporeans First party (SingFirst), of which he was a founding member and chairman.
He regards politics too as a marathon. In this, his third time at the polls, he takes on the People's Action Party's (PAP) newcomer Gan Siow Huang, 45.
"My belief is that you cannot have a super majority of any political party in a Parliament. In 2011 when I went in, it's the same belief, that we need to deny them the two-thirds majority," he told The Straits Times. It is a message he has repeated consistently since he joined Dr Tan Cheng Bock's newly minted party in March this year.
"So as long as Singapore has a super majority, and as long as I can, I would like to be involved (in politics)," added the father of four, who is married to a university lecturer.
Dr Ang spent 23 years in the Singapore Armed Forces, where he headed the psychological medicine branch. He left the army to start his own private practice in 2003, and now runs a clinic at Paragon.
His past political pursuits saw the SDP take 39.9 per cent of the votes to the PAP's 60.1 per cent in Holland-Bukit Timah GRC in 2011; while SingFirst took 22.3 per cent to the PAP's 77.7 per cent in Tanjong Pagar GRC in 2015.
SENIORS, MENTAL HEALTH ISSUES
This time, it is battleground Marymount, the SMC carved out of Bishan-Toa Payoh GRC.
Comprising the Housing Board blocks in Bishan streets 22 to 25, Shunfu and parts of Sin Ming, it has 23,444 voters and covers areas that were looked after by Manpower Minister Josephine Teo. Mrs Teo has moved to helm the PAP team in Jalan Besar GRC.
Dr Ang sees Marymount as "a microcosm of Singapore".
"On the west of Marymount Road in the Shunfu and Sin Ming industrial areas, we have rental flats and three-and four-room HDB flats... then you cross over to the east, where in Street 22 there are clusters of HDB blocks that are mainly four-rooms and above, and the condominium Clover Park.
"It's very representative of Singapore and it forces us to address a wide spectrum of issues," he said.
While he has been walking the ground for the past six days, having covered 10 blocks in five hours on one of the days, Dr Ang is acutely aware that this is as much an online battle as it is a physical one.
Hence, he too is attempting a digital charm offensive for this election, taking cues from 80-year-old PSP chief Dr Tan - who has embraced social media and built a burgeoning Instagram presence of about 33,000 followers.
The day after successfully filing his nomination papers at Deyi Secondary School last Tuesday, Dr Ang debuted a T-shirt specially made for walkabouts with his face printed on the front, and a QR code - leading to all six of his social media platforms - on the back.
Besides Facebook live streams updating his followers on his progress on the campaign trail, he has conducted Zoom webinars with residents of Marymount. The most recent one on Saturday saw him sharing his manifesto - Making Marymount A Model Constituency - and fielding questions from them.
Many questions and concerns were related to municipal issues, like the need for a feeder bus service to take residents directly to Bishan and Marymount MRT stations and Bishan North Shopping Mall, and trash management issues at certain blocks.
They also asked how he would use his expertise in mental health to help senior citizens; where funding for his proposed "social safety nets" for the vulnerable in the community would come from; as well as, if elected to Parliament, whether he would bring up their concerns about the Protection from Online Falsehoods and Manipulation Act (Pofma) curtailing freedom of speech.
Among the solutions and proposals he spoke about during the webinar are lifelong learning centres for the elderly where computer courses can be introduced in a more structured way, and plans to fight for the right to insurance coverage for mental health illnesses.
"Insurance companies are reluctant to cover mental illness because it cannot be seen and it's very subjective, but I propose having a panel of three psychiatrists who will determine if your illness is clinically proven.
"(This is) so that Singaporeans don't have to hide their mental illness," he said.
Dr Ang was formerly the president of the Singapore Psychiatric Association, and he also chaired the Action Group for Medical Illness, which seeks to improve the quality of life of the mentally ill.
WOMAN GENERAL AS OPPONENT
Among the questions he gets asked a lot is what he feels about going up against the PAP's Ms Gan, who he has previously dismissed as a "paper general".
"In terms of qualifications, ability and achievements, my worthy opponent has got it. You don't become a brigadier-general if you don't have the ability. But in terms of values, principles and beliefs and helping the community, I am far more experienced."
His leg-up on the competition? The over 15 years of grassroots experience he has amassed, as former chairman of the management committee of Punggol Community Club, and secretary of the Kampong Kembangan Citizens Consultative Committee, helping then PAP MP George Yeo.
Dr Ang was briefly a PAP member in the early 1990s, but eventually distanced himself from the party because of disagreements over issues like high ministerial pay and the blurred boundaries between grassroots organisations and the PAP.
His genial way with residents on the ground is apparent, where he is ever ready with a booming "hello" and an enthusiastic fist bump.
Last Thursday, he said he and his team did house visits on Wednesday and a good share of those who opened the door to them said, "You have my vote". Some were undecided and wanted to mull over the matter, while the rest had made up their mind.
It seems some residents like retiree Kennie Goh, 72, are ready for change.
"I think Singaporeans have had enough," said Mr Goh, who has lived in Bishan Street 23 for 19 years.
"If you have one more opposition (MP) in Parliament they can at least hear and voice my concerns...if not everything the PAP suka suka (as they wish, in Malay) make changes overnight," he added.
Dr Ang said his party plans to go the distance: "PSP is in politics on the basis that one day we will form a government. Once we are in Parliament, we will establish ourselves as a credible opposition - it's not impossible."