President Halimah Yacob wishes all working people a Happy May Day.

She noted in a Facebook post that while the challenges facing workers today may seem insurmountable, she is confident in their tenacity to overcome the odds, adding that all workers deserve to have this day dedicated to their labours.

"Having spent more than three decades of my life serving the labour movement, May Day will always hold a special meaning for me," wrote Madam Halimah.

"Singapore has come a long way and our workers can be proud of their contributions to build this nation. From our environment workers who toil daily to keep our living space clean to the high-tech workers seeking solutions for our various needs - young and old, male and female - you have done your part and you deserve a special day dedicated to you," she added.

Madam Halimah spent most of her working career in the labour movement, joining the National Trades Union Congress as a legal officer in 1978 and rising to be its deputy secretary-general from 2007 to 2011.

In her post, she noted that the challenges facing workers today are "vastly different from yesteryears".

"Disruptions are more common and more frequent, particularly those caused by technological change. Skills, which in the past helped a worker keep his job from start to retirement, will become obsolete quickly," she said. "Workers will need to be adaptive and always willing to learn new things. I've seen that myself, as factories that I used to visit the first time in the past, never stayed the same when I visited them again.

"But I have great faith in our workers," she added.

Madam Halimah recounted how, during the global financial crisis in 2008, a factory had to retrench some workers and redeploy others. The redeployed operators, who were mostly women in their late 40s to 50s, were asked to go for computer classes.

"The union was worried because some had never touched a computer before, but they surpassed our expectations," she recalled.

"Their tenacity in the face of challenges was remarkable. We have that spirit and we will overcome no matter what comes in our way," she said, wishing all workers a happy May Day.

Madam Halimah will also meet Singaporeans planning to visit the Istana Open House today.

She will launch a Lego model of the building, specially commissioned to commemorate the Istana's 150th anniversary.

Various activities have also been lined up, including dance and music performances by school groups and a Journey To Space exhibition, where visitors will be able to control models of a Mars Rover and an artificial intelligence car. They can also take a closer look at the sun using a special solar telescope, and launch water or dry rockets at the Istana lawn.

There will also be booths for henna painting, balloon sculpting and ice cream.