Mary Ann Sieghart: If I can stick to a New Year resolution, so can anyone

The key is to be kinder than usual to yourself, and to get the stick-carrot ratio right

The other day, I stumbled on a diary I had started in my second term at university. On the first page, I wrote that I had resolved, for once, to keep a diary going for the whole year. In the second entry, I beat myself up about my prodigious talent for procrastination. The third entry chronicled the usual student shenanigans. And the fourth? Silly question, really. There was no fourth.

This pretty much sums up a life of failed New Year's resolutions. I start with enthusiasm, keep it up for a few days or – if I'm really determined – a few weeks, and then, some time in January or February, my resolve weakens until, in a miasma of self-loathing, I find myself reaching for the lift button rather than taking the stairs.

But last year, for the first time ever, I managed to keep a New Year's resolution. I am still astonished, and am not quite sure how I did it. But my tentative conclusion is that you have to be kinder than usual to yourself and get the stick-carrot ratio right.

Last January I decided that I was going to take up running. A combination of a bad back and fear of decrepitude forced me to conclude that I had to start taking proper exercise. The odd yoga lesson or walk from the Tube wasn't going to cut it. Trouble was, every time I had tried before had ended in humiliating failure.

In my 20s, my insanely fit boyfriend took me for a "jog" around the park and I turned beetroot and nearly collapsed. Every five years or so after that, I would try again. The pattern was always the same: I would run far too fast down the street, circle the block, go purple in the face, get a stitch and give up. "I know running is supposed to make you feel good," I would wail, "but I just can't get over the hump."

Why it took me so long to Google "how to start running", I've no idea. I suppose I assumed that if I couldn't do something well from the start, it wasn't worth doing at all. I have enough Type A personality traits not to enjoy failure or even mediocrity. But, a year on, to my surprise, I have discovered that being a mediocre runner is a hell of a lot better than being no runner at all.

And the secret to being a mediocre runner rather than no runner at all is to start slowly – very slowly. You "jog", or in my case shuffle, for only about a minute, and then slow down to a walk again. Then you shuffle for another minute and walk again. Do this just a few times and then walk home. Within a few days, you find that you can shuffle for two minutes before walking again, and then for three.

The improvement is gratifyingly quick for impatient types like me. It was only a matter of weeks before I barely needed walking breaks at all, and my shuffle morphed into something resembling a jog. After less than three months, I was running two-and-a-half miles, further than I had ever run in my life.

Not fast, mind you. I had to curb my instinct to speed up when a Paula Radcliffe type sailed past me. Being slow and dogged is not generally my way of doing things, but I learned that it was the only way to get fit without giving up.

Two things really helped. One was that an equally unfit friend suggested we both sign up for the London 10K race in July. It seemed an unfeasibly hard challenge at the time, but fitter friends assured me that I could do it. They then persuaded me to raise money for charity. The distance felt embarrassingly paltry compared with the marathon and triathlon appeals that normally peppered my inbox, but I duly set up a JustGiving page explaining that, before Christmas, I could barely run for a bus, so 10K was a long way for me.

Once the pledges started flooding in, I was committed. How, otherwise, could I explain to these generous friends that my New Year resolve had sputtered out in February? And how could I admit to IntoUniversity, my chosen charity, that I couldn't be bothered after all to train for this race? Shame was a potent tactic in forcing me out of the front door in an unbecoming tracksuit.

The other was Jonny Wilkinson. He and I are now the very best of friends. "Awesome job!" he tells me as I arrive back home. "Pat yourself on the back!"

"Thanks, Jonny," I reply. "I will."

Jonny's voice arrives down my earphones from my miCoach app. Every two minutes, my music fades down and Jonny says something like: "Time: 10 minutes; calories: 97; distance: 0.91 miles; speed: green zone, 10 minutes, 56 seconds per mile." The app sets an entire training regime for you, based on your height, weight, sex and fitness level and the date of the race you want to be able to run.

Using GPS, it tells how fast, when and where I am running. When I get back, I can see on a chart exactly how quickly I have run each mile, how far I have gone and how many calories I have burned. Over the past year, this has amounted to 320 miles, 66 hours and 36,000 calories. That's a lot of jam doughnuts.

You don't have to have Jonny as your coach – in fact, I might get a tad jealous if you do. You can choose Andy Murray, Jessica Ennis or Victoria Pendleton. What the voice does, though, is keep you going. You have the illusion that he is looking over your shoulder and would be cross and disappointed if you gave up before the end.

When 10 July finally arrived, I was dead nervous. Would I last the course? Luckily the day wasn't too hot, but I had to resist the urge to speed up my plod as faster runners flashed past. I kept telling myself that this wasn't a race but a run – all I had to do was reach the finishing line.

Which I did – not fast, but that wasn't the point. The point is that IntoUniversity is £3,000 richer, I'm half a stone lighter, and I've entered next year's race just to keep the pressure on. Running has now become a habit and at last I am relatively fit.

I don't always manage to run three times a week and sometimes I don't go out for very long. But that doesn't matter either; in fact it is the only way to go. Half way through life, I have learned a very good lesson: if you are kind to yourself and curb your perfectionism, you just might be able to keep your New Year's resolution after all.

m.sieghart@independent.co.uk / twitter.com/MASieghart