Right up to a month ago, I was convinced 65 was too young to retire.

I argued for a higher pension age. My argument was fairly uncompromising. The word zealot comes to mind.

I was pretty firm that, because 65 is the new 40 and we can now expect a good 25 years of life beyond that, everyone should work a bit longer.

Somewhere in my argument was probably a suspicion that anyone who quit and took the pension at 65 just secretly hated their job.

A month ago, I picked up a hammer to start renovating our house and realised I was wrong.

Pulling a deck apart is hard work. You'd be surprised how much of your back you need to put into wrenching the deck timber from the joist below. I never knew the nails wouldn't come up with the timber. So, that means you also have to pry each of the 300 nails up. It's a bit like using a hammer to pull a picture nail out of Gib, except you need the weight of your whole body to get that little bastard out.

After a day-and-a-half of that, the ache in the small of my back forced me to walk with a backward tip like a woman in the ninth month of pregnancy.

Next, I laid the deck. Did you know that to nail in the really long nails you need for a deck you have to hammer with your whole torso? I mean, you lift that hammer above your head and slam it down like you hate that nail. My record was slamming one nail in with only six hammer strokes. More often it took about nine. I did that more than 300 times.

The pain in my hands took me by surprise. After a weekend of hammering, painting and carrying, my hands were really sore. They just lay in my lap like empty gloves and ached. The pain only really left four days later.

The experience has made me realise what work is like for tradies. I can do as much or as little as I like daily, but they do this hour upon hour, every day of the week. By the time they get to 65, some of them will have been doing it every weekday for almost 50 years.

By 65, tradies must be worn out. Tired. Suffering the aches of a hundred million hammer strokes and thousands of timber boards stacked on shoulders. And it's not just tradies ground down by physical work. It's hairdressers, old-age carers, road workers. How can we ask them to delay their retirement? How can we tell them we want another two years of work?

I'm embarrassed by my once hardline stance on lifting the retirement age because it now feels insensitive and indifferent.

I realise I only advocated delayed retirement because I had no idea what actual hard work is. I've spent much of my post-university working life sitting down. It's much easier to do another two years of work when you sit on your butt five days a week.

I now notice that virtually everyone else who advocates delayed retirement is also a desk worker. White collar, professional, financially secure.

So, I've changed my mind on the retirement age entirely. In fact, I've come to believe those physical workers who can't make it to 65 should have the option of retiring at 60 on a lower pension.

If you believe the age should be lifted, take a look at the job you do. If you're a deskie, you probably have no idea what you're asking of some of this country's hardest workers.

Heather du Plessis-Allan is on Newstalk ZB Wellington, weekday mornings, and is a columnist for the Herald on Sunday.