He might have formally retired over a decade ago, but Mr Tan Pheng Huat, 64, continues to impart his knowledge to others.

He recently created a mobile application, called StartBizUp, to help start-up companies calculate their initial costs and the funding required.

Anyone with problems or questions can also e-mail him and receive his help for free.

The message that Mr Tan wants to send is that retirees should not be cast aside, because they have much to give back to society based on their years of experience in the workforce.

"Many of the baby boomers in the generation which I belong to have tremendous expertise and talent. Unfortunately, the majority of them start to lose their jobs in their fifties. Many of them have university education and some have postgraduate degrees," said Mr Tan, who is married with a teenage daughter.

"Even with their impressive qualifications and experience, most of them are unable to gain meaningful employment after that," he said.

"What is sadder is that their wealth of expertise and talents go to waste. The ex-chief executive officers could mentor would-be entrepreneurs. Ex-HR (human resource) managers could help young people with their career development. Each (retiree) can have more than three or four decades of experience."

Mr Tan's own journey has been an eventful one.

He was the director of franchising and small and medium-sized enterprises in Spring Singapore in the 1990s, before he retired early in 2004. The reason for his retirement was health issues that set him back, after he contracted hepatitis B in 1999 and needed a liver transplant.

He also dabbled in his own Internet cafe business before becoming an adjunct lecturer at Nanyang Polytechnic in 2012, imparting his business knowledge to students since then.

He said: "I think it's important to keep learning and then use that experience to help others. Retirees aren't useless or outdated. Their expertise can still be put to good use in the community."

Sue-Ann Tan