YOU'RE only as old as you feel.

You don't look your age. You're younger than your years. Act your age. And other such sayings.

This week I am concentrating on ageing. Is age just a number, or should we necessarily slow down as the years creep upwards?

I am 55, getting near to later middle age. And while I am fit and healthy, time has taken its toll. I have lines on my face, no hair, a few dodgy joints, I literally creak when I move in certain ways, and I sometimes feel dog-tired in a way I would never have in my youth.

At Lafferty Manor, we have just had a new kitchen put in, and the First Lady marked its completion by saying "Right, this will see us out". I feel like booking the undertaker already.

On the other hand, I have no intention of slowing down on my exercise and sport.

At karate class the Sensei sometimes pokes gentle fun at me when talking about techniques that were more common in the past, but no-one gives me an easier time in fighting, or expects me to do fewer press-ups or high kicks than the young ones.

IAM training for the Great Scottish Run half-marathon in seven weeks, and looking ahead to next year's season of races.

Age does not come alone. In spite of my mentor Start Trek's Bones McCoy's advice that all you need to live longer is to "Eat right and get plenty exercise", I am swimming against a tide.

It becomes inexorably harder to be active the older I become, and muscles and bones do get sorer and slower. Getting going in the morning takes longer, a day's office work sees me more exhausted now than before. Will I still be doing karate and marathons when I am 65, 75?

My karate Sensei for many years, Donald MacInnes, a well-known and highly respected instructor, referee and adminis-trator, retired earlier this year. He is fit and healthy, other than the odd joint pain, but simply stopped when he reached 70.

He handed on his ancient threadbare but iconic black belt to another instructor at the end of his final class, and has left karate teaching. That said, he will no doubt remain active, not least on the golf course.

It is funny how perception of age changes. I realise I am now a senior member of the legal profession, having been a solicitor for 33 years and spent a year as President of the Law Society of Scotland.

I think of myself as a working lawyer, still developing and learning. But some of my colleagues are winding up their businesses, letting younger partners take the strain, and some have retired already.

I am older even than the apparently ancient sheriffs and senior partners I dealt with when I was an apprentice, and I guess I must appear to many younger solicitors as an old fogey, though hopefully not terrifying as I found my seniors in the 1980s.

I happily recall a lawyer I worked with, one Robert Turpie, a consultant solicitor at Ross Harper. Bob was in his 80s but still game. He could be absent-minded and called all of us "son", but was able to charm clients and sheriffs with his Falkirk grandfatherliness. One day when chatting, and the matter of his age came up, he smiled and said "Ach, young Austin, Ah'm still just a boy at heart".

Perhaps it is less important how we are physically than mentally and even spiritually. That's where that young at heart saying comes in. We all know people of all ages who have a zest for life, just as we've also met those who are negative and down about everything.

Increasing age and diminishing fitness can be something to be overcome or even ignore by an optimist, but yet another reason for surrender by those of a pessimistic disposition. Feisty and youthful grannies are better than sombre young adults any day.

I don't believe that we are prisoners of our bodies or years. We can all take a look at our physical state and mental attitude. If there is one thing this column has been about, it is that.

I can't be a Commonwealth athlete, nor can most of you. But I keep trying my best, and that involves questioning where I am and how I can change things for the better. As I have grown older, that process has become more important and intense.

I may be grey and grizzled, with dodgy knees and a few pounds more than I need, but for now, as is the title of this column, I am still in the running, and like Uncle Bob, just a boy at heart.