OK… here's the number: 21. Memorise it, then eat this newspaper. You will be sent further instructions by a pigeon wearing dark glasses.

Oh, all right then … I'll tell you now. Your mission is to stay healthy in the coming winter months. And please, please check on oldsters you happen to know. 21C (70F) is the temperature Age UK recommends for your living room.

Older people, and others who are vulnerable, can worry about bills and take risks. So if there's someone like that in your family, it's worth being aware that, additionally, 18C (64F) is the recommendation for bedrooms, while experts warn that below 15C (59F), the cold can raise blood pressure. That, in turn, can ramp up the risk of stroke and heart attacks, as well as generally increasing vulnerability to illness.

So this is serious, right?

I was reminded of these figures, last week, in a quiet moment while doing a shift on the reception desk at Age UK Norwich. There's a wide range of free leaflets there, at the drop-in advice centre (62 London Street) on everything from driving tips for older people, through internet advice or avoiding falls to claiming benefits. So come in and have a browse.

The one I picked up is called 'Winter Wrapped Up', and is full of clear, simple tips on keeping warm and well in winter. (Incidentally, it has a free thermometer inside.)

Here are a few pointers.

The first thing the guide emphasises is - book that flu jab. They're free for those over 65 or people with certain medical conditions. So ask your GP. The vaccine takes 10 days to kick in, so it's good to do it early.

That covered, tip two is… try to stay active.

"When you're indoors, try not to sit still for more than an hour. Get up and walk around and spread out any chores throughout the day. If walking is difficult, you can do chair-based exercises."

And - tip three - remember to eat well. That's important at any time, but "hot meals and drinks help to keep you warm, so eat at least one hot meal each day and have hot drinks during the day".

If it's cost that's worrying you about turning on the heating, talk to our advisers in Norwich by calling 01603 496333.

They can run a check to see if you're getting all the benefits you're entitled to.

If you're elsewhere in Norfolk, our sister charity, Age UK Norfolk offers similar advice. Call them on 0300 500 1217.