One marathon is more of a physical trial than most of us would ever consider undertaking, but how about three in as many weeks?

Not content with just completing the London Marathon on April 23, primary school PE teacher Henry Goldsmith also took on the Manchester Marathon on April 2 and the Brighton Marathon on April 9.

You might be tired just reading that and the 25-year-old certainly found it tough going, but the aches and pains in the days that followed have been well worth it.

Mr Goldsmith, who will marry partner Stephanie in the summer, said: “My wife-to-be’s niece, Sienna, was diagnosed with cystic fibrosis from birth and as a result over the past four years I’ve now run seven marathons to raise money.

“I’ve done Brighton three times, London twice and the Manchester and Paris Marathons, all for cystic fibrosis.

“Running has never been my sort of thing, I was more of a footballer, but it was the only thing I knew I could do to raise money and help people.”

So far he has raised £7,500 including Gift Aid for April’s triple marathon effort, taking the total he has raised for the charity to £18,000.

The secret to such endurance? Ice baths, lots of oily fish and chicken and the incredible crowds that flock to each run doesn’t hurt, either.

Mr Goldsmith, who lives in Ingress Park, Greenhithe, said: “I love my food and healthy eating’s always been hard, but it has to be done.

“London this time was the hardest even though it was my quickest time. My body had been through so much and I was so tired, but the atmosphere was amazing and it was so busy.

“I break the marathon up into two sub-races. I run the first 20 miles and then I know I have got no more than an hour left to run and it becomes a completely different race psychologically.”

His time in the capital this year was three hours, 46 minutes and 23 seconds, which he will be hoping to beat when he takes it on with his cousin next year.

The former Wilmington Grammar School for Boys pupil also wants to try the New York Marathon by 2019, again in aid of cystic fibrosis.

You can still donate to his online fundraising page for this year’s races at uk.virginmoneygiving.com/HenryGoldsmith.