SUPERMODEL Christie Brinkley turned 65 last week, but declared her 'spirit age’ is much younger.

She says that for many years she has never felt her age and ‘turned 50 for the 15th time' at a birthday bash in New York.

I know what she means. I honestly can’t believe I am 58 years old, less than two years away from 60.

When I was young, 60 was seen as REALLY OLD. In fact, we children saw anyone aged over 30 as old, but 60…to us that was one foot in the grave.

Nowadays, 60 is seen as relatively young, with many of us expected to soldier on for another 25 or 30 years, if not more.

I still do a double-take when, some days, I glance in the mirror and see a mature woman’s face, with crows’ feet, wrinkles and dry, crinkly hair, looking back at me. Because in my mind I am still about 20 years old. This is probably my spirit age, the one I mentally revert back to, when I was a young student - happy, lively and optimistic about the future.

It was a carefree time when I would go out clubbing with friends until the early hours and still get up for college the next day. I could run fast, do a decent cartwheel and had a sense of adventure, boundless energy and a lust for life.

In my mind, these things are still very much part of me and very doable, but in reality I know they are well and truly consigned to history and will never again resurface.

The last time I stayed up socialising well after midnight, it wiped me out for the next three days. I was still catching up on sleep a week later. It was simply an evening with friends - there was no noisy, sweaty night club involved, no dancing, and no waiting around at 4am for night buses chomping a greasy kebab. Yet it still left me weary.

I now observe my daughters doing such things and ask myself “Did I once do that?” I find it hard to believe that I really did. It’s like looking back at a totally different person.

Sometimes your spirit age gets the better of you and breaks through. A year ago, on a trip to a stately home, I watched a group of children doing cartwheels and spoke to them about how I used to love doing them. It ended up with me having a go and thoroughly embarrassing myself. I was as supple as an iron rod and could barely lift my legs off the ground. The youngsters thought it was hilarious.

A couple of years ago I entered an adults’ race at a village carnival and, afterwards, it felt like my lungs would burst and my legs would cave in under me.

And more recently I attempted to climb an apple tree in my parents’ garden, as I regularly did as a child, to a bough from which I used to jump down. It is only a small tree, and yet within moments of starting I felt jittery and knew I couldn’t do it. I have hung on to the memory of being agile and fit, and it is hard to let it go.

I’ve lost many things I had at my spirit age. I don’t even possess a sense of adventure anymore - I have little desire to head out and sample new experiences. I am a creature of routine, quite happy at home doing the same things week in, week out.

I was a completely different person aged 20. I could easily slide into a size 8 skirt and confidently wear it above the knee - that’s another thing that definitely won’t happen again in my lifetime.

The much-used phrase ‘you’re as young as you feel’ is a load of baloney. ‘Young at heart’ is far more apt. Most people, especially those of us aged over 50, are young at heart, but we need to remember that we are old everywhere else.