Maybe it's because I can take great satisfaction from saving either my bus fare or parking charges for the car. Maybe it's because I'm an eco-warrior, out to save the world with one less car exhaust pipe contributing to climate change. 

Whatever the reason, I'm a born-again cycle commuter. And it's become something of an addiction - maybe it's all those endorphins pumping round my body. Unlike many cyclists, who hang up their fluorescent jackets when it gets cold, I'll be continuing this winter.

It started in the summer on an old mountain bike that had been sitting neglected in the garage for far too long. All it needed was a bit of air in the tyres and oil on the chain - and all I needed was a pair of ratty shorts and an old T-shirt. Before long I was convinced of the benefits of those cycling shoes that clip into your pedals. What a difference they make, especially going uphill. I didn't even fall off while I was getting used to them. Then the tyres on my mountain bike were switched to a pair of slicks, so I no longer felt as though I was pedalling through sand.

Now, much to Mrs G's embarrassment, I've gone for the Full Monty - skin-tight bib tights, bright yellow jacket, stretchy skull cap under the helmet and waterproof gloves. It might not be flattering, but it's certainly effective.

The benefits of a daily commute are unquestionable. I work up a healthy sweat twice a day going to and from work, without spending money or precious time. In fact, I get to and from the centre of Glasgow from the south-side suburbs quicker than any car, bus or train could take me - that's a fact. And when I arrive, I'm brighter and more energised than I could possibly have been if I'd been sitting on the bus - and certainly less stressed-out than if I'd been driving.

In terms of my health, I could even be prolonging my life. A study of 17,000 Harvard University graduates examined the relationship between mortality rates and physical activity of men aged from 35 to 84 and found that those who cycled 60 miles a week from the age of 35 added two and a half years to their life expectancy.

David Ogilvie, formerly of the Medical Research Council at the University of Glasgow, now at Cambridge, wrote a paper in 2004 promoting cycling as an alternative to using cars. "If you are physically active in general, you are less likely to suffer from a range of chronic diseases, especially heart disease, diabetes and colon cancer," he says. "Some people don't like going to the gym or don't have the time, but they still have to get to work and back - so the best way of getting the required amount of physical activity is to embed it into your daily routine."

He also cites a study from Copenhagen from 2000, which found that people who cycled to work had a 40% reduction in their mortality rate over a 15-year period.

So, you're potentially increasing your life expectancy by cycling, but isn't sharing the road with the buses and taxis just as likely to shorten your lifespan? It might seem a bit scary, the prospect of jostling for position on a pot-holed road with daredevil drivers. But once you've been out on the road a few times, you'll find your confidence grows -and as long as you can show drivers that you have as much right as them to be on the road, they should leave you plenty of space.

"We encourage positive, or assertive, cycling," says Ian Maxwell, from Edinburgh-based cycling campaign group Spokes. "That means taking a position in the middle of the road, as opposed to over next to the kerb. But cyclists also have to be considerate of other road users."

Government statistics show that a cycling death in Britain occurs less than once every 18 million cycling miles, and that a serious injury occurs less than once every 900,000 cycling miles. The British Medical Association, in its report Cycling: Towards Health and Safety, concluded that the benefits of cycling outweigh the risk of injury. And there's always safety in numbers - the more people who cycle to work, the more likely we are to be safe.

The big question now is: can I keep the commuting going through winter, with everything that the dark city streets can throw at me? If you want to keep going, getting the right gear is essential, says Neil Bilsland, manager of Billy Bilsland Cycles on Glasgow's Saltmarket. "There are several things to consider if you want to keep commuting through the winter, both for you and your bike," says Bilsland, who commutes year-round, whatever the weather. "For your bike, you need to get a set of full-length mudguards, to keep both you and it clean. Clip-on mudguards are OK, but for better protection you really need the full-length ones.

"The other essential for your bike is to make sure it's visible in the dark. I use a combination of five lights, three on the back and two on the front, with both solid and flashing options. Whatever lights you use, check they're waterproof - and always carry at least one spare."

Bilsland also points out that, by law, you have to have at least a red rear reflector and amber pedal reflectors, while white front reflectors and spoke reflectors will also help you to be seen. And don't forget your bell - it's a lot more civilised to use one than to shout "hey!" as you speed past pedestrians wandering into your path.

With the bike kitted out, it's important to make sure you arrive at work ready to function. Thankfully, the technology has moved on from the days when the only option for trying to stay dry was an enormous cape that you draped over the bike. Nowadays, it's all about layering, with the one essential component being a decent waterproof jacket. "You need to be prepared for the worst if you're commuting in Scotland," says Bilsland. "You can set off in the morning in good conditions, and on the ride home it could be bucketing it down.

"What you decide to wear depends largely on what kind of facilities you have at work, and also on what you need to wear once you get there. If you have access to a locker and shower, it's easier to change once you arrive. I wear my work clothes with a protective layer over the top, so waterproof trousers, jacket and gloves are essential, but I leave a clean pair of shoes at work."

Top-of-the-range manufacturers such as Assos make cycling tights that are suitable for whatever temperatures you are riding in, and will dry out even if you get wet on the ride in. If you do end up carrying a change of clothes, it's worth investing in a decent set of panniers. Some of these come with commuting in mind, with models such as the Ortlieb Office Bag looking more like a high-tech briefcase.

Cycling to work might mean making an investment, but when you consider what you're saving in terms of fares or petrol and parking fees, it all adds up. US Congressman Earl Blumenauer couldn't have put it better when he said: "Let's have a minute's silence for all those people who are sitting in traffic on the way to the gym to ride a stationary bicycle." No excuses: it's time to get saddled up

I haven't cycled since I was at school: All the more reason to get back on it. Take it easy at first and try out a couple of practice runs.

My bike's gathering dust: You don't need a top-of-the-range bike for a daily commute. In fact, you'll be better off with something that's going to take a bit of wear and tear. Clean it up and get riding.

I don't fancy the traffic: Turn road rage to road bliss - when you sail past stressed-out drivers, you'll never want to drive into town again.

I'll get punctures: Not any more. Tyre technology has come a long way, and the best tyres nowadays are virtually puncture-proof.

I don't have a bike: Pick up something inexpensive and functional second-hand to get into the swing of things first.

I have to wear a suit: You can get panniers now that are designed to carry a suit without creasing it too much.

I'll smell at work if I can't take a shower: Give yourself a quick once over with a damp facecloth and carry whatever products you need to make yourself look, and smell, presentable at the morning meeting.

I live too far away: Then consider a part-commute, where you take public transport or the car a certain distance, and then jump on the bike the rest of the way.

The exhaust fumes will kill me: Research has shown that drivers are actually exposed to higher levels of pollution inside their cars than cyclists are outside. Spokes has a new cycle map for Glasgow available in bookshops and cycle stores, priced £4.95. Billy Bilsland Cycles: 0141 552 0841 or www.billybilslandcycles.co.uk.