HABIT.

That's this week's word. Both meanings, First, clothing - you know the old joke: you can kiss a nun once, twice even but don't get into the habit.

And second, repetitive personal behaviour. Both are significant in health.

My mother-in-law - no, don't worry I am not doing mother-in-law jokes, not least because mine does not remotely resemble a music-hall battle-axe but is an excellent person, has a habit of noticing my weight.

When she asks if I have lost weight, I know I must be on the right track. If she doesn't ask at all, it is because it has increased and she is too nice to say. Her habit reflects on my habits.

Taking up running again this year was a break of habit - I had got into a routine of eating and drinking too much, doing only limited exercise and staying well within my comfort zone.

I am no nutritionist, but it is logical that the older you get, the slower your metabolism works and the less physical exercise is taken. That all adds up to weight increase and health decrease.

As my marathon training ramped up, it was obvious that miles pounded meant pounds lost.

So running became what management gurus call disruptive change. Indeed, exercise has become the new habit.

But unlike my previous one, it is a habit of will and decision, even determination, rather than passivity as previously.

That, frankly, is because I do not actually enjoy running.

It is a hassle, hard going in bad weather or darkness, and often sore. Indeed as I write, I am nursing an odd glitch in my right foot that gives a sharp pain if I put weight on it at a particular angle. But my conscious will overcomes these dragging factors, for two reasons. One is that I need to train for races, as simply rocking up on the day and putting on a pair of gutties is inconceivable. The second is that having tried everything else, the only thing that keeps bulk down is running out of my comfort zone. Training for the Belfast Marathon did far more for me that training for shorter runs since. That's why I am so delighted to be in the 2015 London Marathon - I know the miles endured between now and April will bring me the greatest physical benefit.

And that in turn hopefully will lead to the other habit being brought positively into play.

Apparel and I have a sometimes fraught relationship.

The First Lady is a very sharp dresser. I am not. Let's not use the word scruffy, let's say I am smart casual without necessarily being too smart.

Like most lawyers I have to dress formally, but I usually don't wear a tie unless in court, and I never have my suit jacket on in the office.

I tend to batter business suits to death until there is almost an issue of public decency, when I then go out and binge-buy enough new formal wear to keep me going.

What that activity cruelly reminds me every time is that the numbers on the clothing labels have gone up over the years.

And wearing anything fitting such as T-shirts or tailored shirts shows immediately how my stomach is still not a six-pack, though less of a keg than hitherto.

We clothe ourselves for warmth and decency.

And while there is no law against bad dressing, we can all tell at a glance if someone has chosen appropriately or not in terms of age, social context and indeed weight. Indeed I am being objective, not needlessly cruel in saying many people have not only covered their bodies but their minds when choosing clothes to wear.

"How can she possibly have dressed up like that?" is a common reaction to someone who is obese but clothed in a ridiculous way, either flaunting unwanted flesh or trying to deflect a gruesome image by dazzling outfits.

But clothing should be a catalyst and not ­camouflage.

We should be able to recognise that we are overweight, and instead of just buying bigger sizes off the rail, we can address the cause rather than the effect, and do something about our weight.

The shop changing-room mirror should be our conscience instead of a partner in crime. There is no perfect shape, we are all different.

But there is also a difference between being big-made or broad in the beam as against eating too much and failing to take responsibility.

So my goal in building up miles for the Cockney canter is to get weight down to the right level for my height and build.

I think just over another two stones should do it. And then keep up the two habits of a trim tum, and a medium fit in T-shirts.