LAST week in my Food diary (riveting, wasn't it?) I mentioned two gardening shifts I did at the weekend.

Although I waxed lyrical about the healthy nature of controlling, well, nature in the shape of weeds, grass and earth, it may not be an immediate association with marathon training.

But actually, if you were to strip down exercise to the basics, I would put money on gardening as being better than running - by some way.

If you think back to our primitive ancestors, they survived by being fit for a hard life of hunting, building, clearing, fighting, all of which had to be done manually.

I don't imagine many of them ran very far, other than to go away from a lion or towards a gazelle.

The idea of running continuously from this cave to another two hours away would have been ludicrous, even with a potential mate ready to be hauled away.

But they did need to turn their hands - and arms/legs/ muscles generally - to a wide variety of activities, most involving strength and endurance.

If obesity had been a word then, it would have been a meaningless one. And though I am using the word primitive, the reality is that this need for physical fitness was a major requirement until quite recently.

You could probably plot a graph over the last couple of hundred years for the rise of labour-saving devices, although even back in ancient Roman and medieval times man and woman have regularly sought ways of making lives easier.

But it is the industrial revolution that really saw the birth of the idea of automation and mechanisation as the means of reducing physical effort.

And now in the 21st Century - you can probably go through life dodging exercise almost entirely.

If you've seen the animated film Wall-E, a large part of the action takes place in a spaceship that had taken the last humans from Earth to live in space until the planet was safe for return.

This was their past, but our future. While up there, everything was done for the people by computers and robots.

Over several generations the population had all got incredibly fat, and were moved around not on their own feet but in motorised chairs.

Even the Captain who inherited the official uniform didn't wear the jacket properly but had to let it hang tied loose round his neck and over his shoulders.

He played golf not by swinging a club but by pressing buttons on a computer-generated game on a screen.

Last week obesity hit the news pages of this paper.

At one end there is a suggestion that slimming classes will be made available paid for by public funds, as this will in the long run save NHS cost, and at the other the official advice is to eat three less biscuits a day.

I am not a politician or a dietician so I can't give advice, but I am a taxpayer, and there is something terribly depressing about a society in which we have reached crisis point and have to consider extreme measures to deal with what is not an intellectually difficult proposition.

Calories in, not enough burning of them by exercise and activity, calories stay in, and on.

I know there is no quick fix.

This fat mountain has built up over many decades and will take a similar timeframe to get rid of.

Diet course and advice are very important for sure.

But Doctor McCoy's secret to long life is twofold - eat right…. and take plenty exercise.

Physical activity is essential.

I run - reluctantly but necessarily. But running is by no means the only way to fitness.

There are so many ways of expending calories productively.

Walking, cycling, swimming, Zumba, exercise videos, dancing are all great if done with vigour.

So my alternative exercise is the gardening. Three hours of hefting and labouring, and my lats and pecs are in good order. Bending, pulling, twisting, hauling - all great workout moves.

And then, you get the twin benefits of a lovely looking natural scene, and having gulped God's good air all afternoon.

Then - the satisfaction of sitting in a lounger with a cold drink, surveying your handiwork as the Robins fight over the worms and woodlice unearthed by digging and weeding - sheer bliss.

Not everyone has a garden. But for those of you who do, you have quite literally your own gym outside your back door. And there's no fee due.