There's a weightlifting area in my gym – not just the rows of dinky handweights by the stretching mats, but the bit with the squat cage, the bench press and the machine where, with both hands, you pull down weights the size of hefty toddlers. I haven't used it – yet – but I'm going to. I've been weight training since last year and every session takes me a bit closer to the end of the handweights and the start of serious lifting. I'm looking forward to it in a way I've never looked forward to exercise before.

Personal trainers, however nice, give me PE teacher flashbacks. I'm not co-ordinated so the group classes that others seem to find fun and sociable – "step up, touch down, change legs, grapevine, step change and shimmy" – just leave me feeling clumsy and frustrated. But I can pick up an easily graspable heavy metal object, lift it slowly and then put it down again. Not only can I do it: I find I love it.

I won't deny that some of the appeal is in the symbolism. Getting physically stronger feels like something worth embracing – unlike the goal given out to teenage girls these days of becoming a "size zero". Shauna Reid, author of The Amazing Adventures of Dietgirl agrees. She says, "I like the calmness of weight training. It's hard work but it's simple, honest exertion. It helped tone me up, but the greater benefit was the feeling of empowerment. Weight training helped me like my own body instead of aspiring to someone else's." And, she adds, "It made me see I was strong, and capable of so much more than I'd thought. When the water cooler is empty at work, I can lift that giant bottle of water with ease. When someone can't open a jar, I can say 'Step aside, let me do it!'"

Part of the appeal for me is the enforced scarcity. The amount of aerobic exercise I can do seems almost unlimited – hours tramping away on the treadmill or riding the stationary bike to nowhere. I tried lifting three times a week but it didn't give my muscles time to rest and recover, so I started getting worse. I lift only twice a week now, but barely a week goes by without my finding that some muscle group has got stronger. So I have two precious hours a week raising and lowering those slabs of metal. I start to long for it, to feel impatient for my next session.

Yet Krista Scott-Dixon, who runs stumptuous.com, a weightlifting website, explains that many women have been taught to fear "bulking up" when training with weights. "In our culture, women aren't supposed to be physically strong or powerful, and this idea is still around in 2011. Women are terrified that if they touch a weight, they're going to suddenly turn enormous. People don't understand that you can't develop a bodybuilder's body without years of focused, intense training and huge amounts of drugs."

Scott-Dixon has been training for 15 years and has gained only about 5lb of muscle. But it's enough to make a huge difference: "When you do your first pull-up, or push-up, it's an incredible feeling of accomplishment," she says. "You start to feel like maybe you could do anything. You also conquer fear and apprehension. Getting underneath a heavy bar can be terrifying."

The health benefits for women include helping to prevent osteoporosis. As Dr Benjamin Ellis of Arthritis Research UK says, "lots of women already know the benefits of cardiovascular exercise. But resistance exercise strengthens bones and stabilises joints, helping to prevent injury and the effects of ageing. Our bones and joints have to last us a lifetime – it's never too early to start looking after them to feel great now and prevent problems later in life. Weights aren't just for young men – men and women of all ages can and should reap the benefits."

And those benefits are noticeable. I've put in my time on the treadmill, the exercise bike, the loping elliptical "trainer" (presumably providing training in case my feet are ever replaced with huge springy wheels). My blood pressure went down and so did my resting heart rate. Both these things are wonderful benefits, but I can't say that I really notice them.

Lifting, though, is detectable. It's the moment in the train carriage when I hoist my suitcase into the rack and find that the motion is easy. Or when I trip on a tiny pavement irregularity, almost fall, then feel the bunched muscles of my thighs – all those squats – yanking, hoisting me back upright. I've started to feel my muscles working all the time – I imagine myself as one of those diagrams showing a body with the skin flayed off, all sheets of taut red-and-purple striped muscles. I reach a box down from the shelf and feel the pinioned stretch of my shoulder: deltoids and rhomboids and supraspinatus. Everything seems a little bit easier than it used to be.

The squat cage and the bench press rack are still in my future. But I've taken to staring at them as I walk out of the gym and thinking: soon.