Dublin-born David, who now lives in London, told me: "My mother and grandmother knew that I was interested in empathising with and helping people from a very young age.

"Being Jewish, that meant being a doctor. They geared me up to that. At the age of four I had a doctor's set put in my hands."

However, in his Dublin Jewish secondary school, Stratford College, David was only a B student.

Anxious not to disappoint his mum, Tova Citron, and his late grandma, Maureen Caplin, David pushed himself to "over-achieve".

He said: "I had to find a way to be an A student so I could get into medical school. I had to find strategies to become a better student.

"I am now using strategies to help so many others achieve academic and business success."

But medical school at Scotland's St Andrews University was not exactly to David's liking.

He told me: "At the time, I thought medicine was what I wanted to do. I knew I wanted to help people. I didn't know anything about psychology, psychotherapy, coaching or the success industry."

Then halfway through his St Andrews course, there came a psychology course.

David said: "I was super into it. No-one else was. I was the only one in the room interested.

"I realised that I was more interested in psychology than feeling people's abdomens, taking temperatures and diagnosing on a physical level. I was more interested in talking through and helping people, working things out, strategising and finding ways to improve people's performance mentally."

The three years in St Andrews were due to be followed by three years clinical experience at Manchester University. But first David took a gap year, which became two, at Shapell's College of Jewish Studies, Jerusalem.

A life-changing moment came when David was asked by the yeshiva's shidduch committee about his intended career path.

He replied that he intended to be a doctor, but alarm bells went off in his head.

David recalled: "A voice in my head said, 'No you are not. Liar, liar, liar!'

"At that moment it was the first time I realised that something was not quite right. I spent the whole night pacing around the beth hamedrash wondering what was I going to do."

David did not study at Manchester University. He moved to London, found his wife, London-born Abigail, on an Orthodox Jewish dating website and gained an MA in psychotherapy and counselling.

But halfway through the course, he had a similar experience to that in medical school.

He said: "I liked it. It was almost what I wanted to do, but not quite. I was more strategic, into moving forward. The course was more about the past. I was more about the future, learning strategies and taking action."

By helping out Hendon's Boys Clubhouse, in north London, for teenagers at risk, David learned about life coaching and took a master's degree in neuro-linguistic programming and also did a tremendous amount of research into strategies to help others move forward.

Working with kids with backgrounds of drugs and broken homes, David helped them create visions for themselves by overcoming their addictions and building successful businesses.

He set up his own success strategy practice, using multiple strategies from multiple disciplines to fit strategies to individual clients.

He said: "Each client is unique. What works for one might not work for another."

David told me: "My mantra is to give as much value to as many people as possible. Then great business happens.

"The problem with businesses is when people think they can only do business by pulling the wool over someone's eyes, by tricking them.

"That is not a business that lasts. It's a façade, a scam. I have seen the outcomes of such businesses. They are not sustainable, not an asset to the world, not doing anyone, even the person initially making the money, any good. I am very much about value-based business."

David mainly works with six-seven figure businesses, but he also likes helping entrepreneurs and has helped more than 600 students go from Cs to As.

But he said: "I do love the business world because it's easy to see the results. When someone quadruples their business they tell their brother, who tells their cousin and their neighbour. It's an exciting path."

He reckons that being Irish and Jewish has helped him on his path to success.

He said: "There's a conformity and conservatism in the UK. We shouldn't let that hold us back. We need to be a little more outrageous by being prepared to market ourselves and get ourselves out there.

"I am used to being an outsider as the Irish guy coming in, the Jewish thing also. My theory is that outsiders tend to over-perform.

"One in four American millionaires are immigrants. Jews have outperformed in many industries. When people are outsiders to the norm, they tend to feel they have to work harder."

And David wants to give 10 times more than he receives.

He said: "I always want to make sure I am giving more than receiving. I want to know that I've helped people."

For this reason he is offering his recently-published book, The Winning Mode, as well as business courses, free online on www.davidcitron.co

He said: "I am very happy for people to take a free ride."

And what about his parents, have they come to terms with his failure to live up to their dream of becoming a doctor?

He said: "They found it tough at first. But, years on, they have come to terms with it when they see how happy I am and the effect I am having."