Jesudas Menon, 61
A long-time head of physical education at National Junior College, Mr Menon was in his mid-50s when he retired in 2010.
Way too young to sail into the sunset, he took up an adjunct position at the National Institute of Education the next year to teach sports science.
He had a master's in PE from the University of Oregon, which he completed in the early 1980s. But times had changed and much of what he learnt back then had become obsolete.
So in 2013, the father of two grown-up daughters decided to embark on a second master's degree, this time a research degree in sports science, at Nanyang Technological University. His research involves measuring the impact of exercise and meal frequency on fats stored in the blood.
"The programme has made me update my knowledge and fulfil a long-cherished dream of working in a lab," says Mr Menon, who plans to advance to a PhD programme, which he hopes to complete by the end of next year.
Allan Foo, 63
Like many in his generation, Mr Foo did not go to university. His parents split up when he was in national service and he decided to start work soon after.
In his 30s, he enrolled in evening classes at UniSIM to do a diploma in management studies and then a postgraduate diploma in marketing. He quickly climbed up the corporate ladder, becoming group marketing director of Yamaha music in 1988.
By the turn of the century, he had struck out on his own, opening a marketing consultancy firm, advising retail businesses on how to grow their client base. In 2006, he began a skincare and women's wellness business which is thriving today.
Then, in 2010, the eldest of his four children enrolled at the Singapore Management University to do a double degree in business and law. "Seeing my son at university made me want to go back, to get a proper degree."
By the time his second son enrolled at Tufts University in the United States, Mr Foo had completed an executive master of business administration programme at SMU's business school. Coursework sometimes began at 9am and ended at midnight. "It was exhausting, but I enjoyed every second of it," he says.
What he does not say is that he was voted the most outstanding student in his class.