As fit as a Butcher

Prostitute, cocaine addict and now husband-killer, Charlie Brooks has clocked up some seminal soap moments in her role as

But off the set, Brooks is leading a wholesome life that couldn't be further from her screen persona - quick sprints round London parks, mineral water and bed by 10. It's all for a good cause, since she's in the final stages of training for this Sunday's marathon.

This new regime comes at an opportune time. Having notched up five years on Albert Square (and she's still only 23) Brooks's Janine is about to exit the soap. Rumour has it she'll be leaving to serve out a jail sentence --although the script may leave the door open for the high-drama comeback favoured by EastEnders' writers.

This means Brooks is preparing to launch herself on the casting circuit and find the post-soap stage in her acting career. Training for the 26-mile course is not bad preparation - supreme willpower, major lifestyle changes and the patience to endure those tedious hours on the treadmill.

Brooks is first to admit that she's not a gym natural. 'Before this I'd never really worried that much about fitness or weight,' she says. 'But I decided to run the marathon because last summer Sarah Jones - the older sister of my best friend Kate - died of liver cancer at the age of

25.' Friends and family in North Wales were rallying round to raise money for Marie Curie Cancer Care, which provided nursing and emotional support in Sarah's last months. 'Kate had taken part in charity runs, so she asked me if I would get involved,' says Brooks.

So by last October the two old friends had filled in their marathon entry forms and become running buddies - an essential source of willpower and camaraderie in the ongoing battle with blisters, sore legs and fatigue.

'The training was dreadful at first,' shudders Brooks. 'I couldn't run at all - although I didn't suffer from blisters like Kate. But once you get into the routine it's surprising how soon you pick up stamina and learn to control your breathing, which is the key to successful long-distance running.

You also find that your legs start to carry you along so you don't get tired or out of breath so quickly.' The pair quickly increased the distance and frequency of their runs and in the months to Christmas, they were clocking up two-hour sessions three times a week.

Matching schedules wasn't easy, so sometimes they were forced to run alone (Brooks favouring Hyde Park), but always meeting up to swap stories and relieve the boredom. They had a short, and disastrous, break for Christmas indulgence. 'It was like starting from the beginning again afterwards,' Brooks says, but by early January they were back in tracksuits and trainers.

By this time, their fundraising was attracting additional support. Sarah Williams, a personal trainer at The Dorchester, provided her services and the plush facilities of the hotel gym for treadmill and sprint training, plus advice on diet and nutrition. She helped