"There are two noble things in life: one to do charity and other to look after your body," he said.
"This includes the high principles outlined by my religion, to earn an honest living and to share your means with those less fortunate.
"I am inspired by honest people who don't cheat others. To me the famous are those who are kind to fellow human beings and dedicate their life to charity."
And it is religion that helps him keep going when he hits the dreaded "wall" during a race -- he experiences the transcendental effect of such exercise that was so eloquently documented by Japanese author Haruki Murakami in his book "What I Talk About When I Talk About Running."
"The first part of the run is when I am quite cheerful; my heart is singing a song and dancing seeing the different colors of life," Singh said.
"When I get really tired, I start chanting God's name: 'Waheguru, Waheguru.'
"Running also makes people more spiritually aware and in-tune with their inner self. A retired marathon runner will still retain all these qualities."
And having become the world's oldest marathon runner, Singh is indeed now retired.
His final race was the 10-kilometer event ahead of February's Hong Kong marathon, after which he took the advice of his family and Harmander Singh.
"I have retired because given my age, my body has deteriorated a bit, but retirement hasn't slowed me down," he said.
"I lead a very active and healthy life. I walk for three to four hours a day, play with kids and do all my day-to-day chores myself. I might have continued to run for another year but I realized I had to eventually retire one day."
A strict vegetarian (he appeared in a campaign by animal rights group PETA) Singh describes himself as "an illiterate person" -- this interview was translated from Punjabi with the help of his coach.
While he lives a simple life -- in bed by 10 p.m. after relaxing listening to Punjabi radio, and up again by 6 a.m. -- he does admit to one guilty pleasure: shopping.
"Though I am an old man now, I am still very particular about my personal style. I love shopping for suits and shoes -- I keep looking for the latest and best available," Singh said.
"I don't have many expenses but I do spend often on new suits and shoes even though I have a lot of them."
Running shoes, in particular, remind him of the happiness he has discovered.
"I am very fond of my running shoes, I absolutely love them. I wear them for pleasure. I can't imagine my life without them."