At the time, I was 39 and married with three young children. But I suddenly threw myself in front of a 10-ton truck when I was cycling down a country road. It appeared I had attempted to take my own life – unsuccessfully, obviously. In the preceding four months, I had been signed off work following a dramatic breakdown. I was suffering from agitated depression caused by extreme stress. Twelve months before that, I had joined forces with two outstanding professionals to set up our own company. I had reached the pinnacle of my career.

So, what exactly had gone wrong? And what have I learned from my breakdown that I can pass on to others?

Alot of the damage had been done previously. I was born with two special ‘genes’ – winner and worry. Winner gene ensured that I possessed a competitive streak, always wanting to play, perform and succeed. But the worry gene meant anxiety and stress accompanied me in most things I did. The two didn’t make great bedfellows. Setting up your own business, with all the inherent risk and uncertainty that involves, was never going to be conducive with a personality that worried about most things in life. Aged 39, I still bit my nails.

Introverts get all their energy from within. JK Rowling and Barack Obama are self-confessed introverts. On the other hand, Margaret Thatcher and Muhammed Ali were strong extroverts who were energised by the people around them. Extroverts find their energy being sapped the more time they spend in their own company. It’s the other way around for introverts. As far as my personality is concerned, I am probably 70:30 introvert to extrovert. Although I would have loved to have spent hours on my own, navel-gazing and conceptualising, the nature of the career I had chosen meant I had to be out and about, surrounded by others, socialising, selling and sitting in meetings. That wasn’t me – and I suffered as a result.

Do you get your kicks from ticking things off your ‘to do’ list, completing business plans, launching new products, wading through documents and doing stuff? Or are you more motivated by helping others develop – teaching, coaching and mentoring? The two are quite different. I was definitely more into the latter. I had been a successful management trainer for the past seven years. With the new company, I was now a businessman looking after the accounts and the legal stuff; I was a ‘suit’, having to make key decisions day in and day out. Juggling, prioritising – that wasn’t me either and I missed the sanctuary of classrooms full of eager-beaver students.

So, the first lesson is to ensure that you choose a career where you are a round peg in a round hole.

One area of neglect during my brief stint as an entrepreneur concerned my body and mind. My unforgiving work ethic took its toll. It was normal to start work at 8am, stop at 7pm, eat dinner at 8pm and collect emails between 9pm and 11pm. In addition to a full working week, I would often willingly sacrifice a Sunday morning to catch up or prepare for the week that followed.

This hectic routine was exacerbated by the fact that I was travelling to countries across the globe, often running back-to-back training courses for a week or two at a time. I was stuck in the era personified by Gordon Gekko from the film Wall Street, when lunches were for wimps and burning the midnight oil was the accepted norm.

In hindsight, I now realise there were also clear warning signs. First, I wasn’t really enjoying what I was doing. I saw entrepreneurship less as an exciting challenge and more as a painful burden. Second, I was becoming more and more serious and introspective with every passing day – joking less and laughing less. Third, my sleep patterns were becoming increasingly disrupted. And last, I was losing the ability to make fairly straightforward decisions at work as I became “infected” with hesitation and procrastination.

Throughout this difficult period, I felt unable to confide in my two business partners. In retrospect, this decision not to confess I was in trouble was a big mistake. I think there were three reasons why I found this so hard to do. I did not know either of them very well on a personal level and divulging something this sensitive seemed out of the question.

I also kept trying to tell myself the discomfort I was feeling was perfectly normal and only to be expected. At least, this is what my winner gene kept insisting. Things would get easier sooner or later and I just had to ride out the storm. In any case, most of my friends were under some kind of pressure as they tried to forge ahead in their respective careers. And confessing was not on the cards because I had spent the last two or three years waiting patiently for this big opportunity. I had made it happen.

 The last thing I was going to do was jeopardise it by admitting to either of my partners that I was in trouble or mentally fragile. Although mental illness in the business world still is a taboo subject, it was doubly taboo back in the early 2000s, when there was very little guidance on what to say or do either as a sufferer, a carer or an employer.

So, my second lesson is to ensure that you look after number one as an absolute priority. This is even more important if you find yourself in the wrong job.

But here’s the thing – my breakdown gave me a wonderful opportunity to re-evaluate things. I sat down with my wife, and we plotted and planned a future that was much more in line with how we wanted to lead our lives. At the top of the list of things to agree was how we should balance the demands of work with the needs of our young family. Gekko had to go.

I also had to establish what kind of career would satisfy the needs of both winner and worry genes. I concluded that climbing the corporate ladder was not a good match for my core personality. Neither were the stresses and strains of entrepreneurship. That was now obvious.

I decided to descend the ladder and deepen my knowledge in a specific area of business. I wanted to become an expert specialist rather than a broad generalist, and this was something I could succeed at without putting my mental health at risk again. A win-win for both genes.

So, painful though the experience was, there were some distinct silver linings, and even though I had paid a visit to the depths of the Mariana Trench, I still aspired to climb Mount Everest. But this time, I would do so safely.

My third lesson is to ensure you take the positives from any mental health episode. A breakdown really can lead to a breakthrough.

• April is Stress Awareness month. See stress.org.uk/national-stress-awareness-month
• Mental Health Awareness Week, 15-21 May. See mentalhealth.org.uk