If you think completing one marathon is a challenge, imagine what it takes to finish 12 marathons in 12 months.

Andrew O’Brien has completed that impressive feat to raise money for The ISIS Foundation, a charity founded in Bermuda which helps communities and children in remote areas in Nepal and Uganda.

The London-based actuary completed his final run in the Copenhagen Marathon on May 18. However, he said there were times over the past year when he had serious doubts about whether he would see the final finish line.

After taking part in the Bermuda International Marathon, his eighth marathon, in January, Mr O’Brien started to feel a lot of pain in his leg and an MRI scan showed he had a stress fracture in his calf.

Doctors told him he couldn’t run anymore, but after undergoing weeks of physiotherapy and taking part in a low impact training schedule, which included swimming and cycling to maintain his fitness, he was back on his feet again a month later.

Mr O’Brien said: “I missed one marathon because it was too soon after the injury and it was still healing.

“But I went for a full scan and it showed an improvement so I took a risk and ran in the Atlanta Marathon, followed by marathons in Brighton, Madrid and Copenhagen.”

Although running is relatively new to Mr O’Brien, he said he was inspired to push his body to new limits after a “life changing” missions trip to Kiwoko Hospital in rural Uganda, where his employers reinsurance and insurance group Aspen had a partnership with the ISIS Foundation.

“After going there I wanted to do anything I could to raise money for the people in these communities,” he said. “And the reason I decided on running marathons is because the guy [Stephen Kiprotich] who won the gold medal in the marathon at the 2012 Olympics was Ugandan.

“His win was a huge deal in the country.

“After that I had this idea in my mind that I could do a marathon, but I didn’t want it to just be a one-off thing.

“I wanted to do something that lasted so I could raise awareness and be a testament to the village and people in it as well who I had made a connection with. I wanted to relate my struggle in doing the marathons with their struggle to live and survive.”

Mr O’Brien said each race was challenging in different ways. The Singapore Marathon last December was probably the hardest because of the intense humidity.

He said: “That race started at 5am and by the time I got half way around I was absolutely knackered and I started getting cramps around 30 kilometres and I had another 12 kilometres to go.

“So that’s not a good feeling. They gave me something called Tiger Balm, a rub for pain relief, and I just had to grit my teeth and get things moving.”

The most rewarding marathon for Mr O’Brien took place in Uganda. The race course took him through much of the country’s bush and around the Kiwoko Hospital, which has a special place in his heart.

“That’s the place where this journey all started for me,” he said. “I spent a week at the hospital two years ago and that’s where I got inspired to fund raise after I got back [to London].

“I had never run before going there [for the missions trip], but that’s when I started running.”

In addition to the time he fractured his calf, there were several other instances where Mr O’Brien contemplated giving up.

He said many of the marathons had early starts at 5am or 7am and he would catch glimpses of partygoers just coming home from a fun night out. At those moments he thought to himself, ‘I should be home in bed’.

But he persevered and kept his eye on his goal to raise $16,756 along with awareness about the ISIS Foundation. Thanks to donations from 111 people he reached his fundraising goal this weekend.

He said taking part in this experience has showed him that he can do anything he sets his mind to. “I learned in the past few years that we tend to take a lot of things for granted and what we see as basic items the rest of the world sees as luxury items.

“But what I realised from that is how just giving a little bit of money can go a long way. You can make a big difference in people’s lives just by offering up a little bit of what you have.”

To donate to Mr O’Brien’s fundraising feat visit www.justgiving.com/ISIS12in12.

Useful website: www.isisgroup.org