As one gets older the list of life experiences that “only happen to other people” gets shorter.

People die, friends’ marriages fall apart, the unforeseen becomes visible. Depression was very much that kind of experience for me.

Despite my father having suffered some form of it most of his adult life, I had come to see myself as essentially one of life’s cautious optimists.

Yes, I could worry too much and lose sleep over things that in the light of day seemed trifling, but everyone does that to some extent. Genuine clinical depression was not even on my radar.

For a long time, too, I resisted any idea that I might be succumbing. I had recently quit a highly stressful job – one that required me to give heart and soul to be successful.

But because it was such a demanding role, the constant stress and anxiety tended to get buried under the next rush to deadline. I never stopped to take stock or examine how I was absorbing the pressure. It’s a common enough story.

It was when I finally quit the job – and, in hindsight, accepted another offer too quickly – that the wheels started coming off.

Looking back, I liken it to running too fast down a hill when you’re a child: for a while your legs can keep up with your momentum, but eventually your velocity is too great and you go down. That was what happened to me psychologically.

Stuff bubbled to the surface. The previous job had not only been fast-paced and creative but also carried some prestige.

Without my old title I wondered who 
I was – or who I had become. I’d allowed my public professional self to become confused with my personal private identity to some extent.

My new job in a new industry required that I learn new skills; 
I was no longer in charge – in all senses.

I began to worry all the time. Insomnia set in. Tired and worn out, I was susceptible to my own worst self-criticism. Nothing was in proportion. Life became one long four-in-the-morning anxiety attack. The colour drained from my world.

Still I refused to admit there was anything wrong – other than getting some sleeping pills, which weren’t very effective.

It was only when I found myself shivering on a mild day as if a winter southerly was blowing that I finally gave in and called the GP.

The sheer unavoidable truth of 
this physical symptom made me realise I wasn’t going to fake my way out of whatever was affecting me.

I found myself seeing a therapist and taking an antidepressant (Aropax). Accepting expert advice that I should try medication was difficult – it implied I really was mentally ill, something no one really wants to admit.

Men in particular resist facing up to such truths. So many of us are conditioned to take control, and to view the loss of control as a sign of weakness and failure, that we feel genuine shame about succumbing.

The most reassuring thing I heard at this stage was from my therapist, who said 80 per cent of her clients presented much like I did: outwardly successful, confident people who had tripped up for some reason and found themselves, often to their surprise, flattened by a metaphorical bus.

Another reassurance came from learning more about the physiological nature of my condition. My depression came under the umbrella diagnosis of stress (I joke now that I was suffering from post-traumatic workplace stress disorder), which causes tangible imbalances in the neurochemicals and hormones that govern mood.

It was as though my “fight or flight” instinct was jammed on full. There was no immediate, obvious cause, so the adrenalin never stopped flowing. Hence the constant state of anxiety, the feeling of nameless dread, the sleeplessness and the shakes.

Through a combination of therapy and medication – I don’t know in what ratio they were effective, but they were – I recovered my old equilibrium.

The clouds of doom passed and ordinary everyday problems resumed their proper perspective. Eventually I weaned myself off the Aropax. While it may have filled in the troughs in my mood, it also seemed to blunt the peaks. Bland was better than blue, for sure, but in the end I wanted my emotional landscape unfiltered.

The trick is to see the lows coming, to recognise those tendencies in yourself to dwell or fret or obsess until you’ve created a mountain of despair out of a molehill of needless worry. Exercise is good. Learning to block negative thinking is, too, and it’s surprisingly easy to do with a little help from a trained professional.

I don’t for a minute think my depressive episode was in the same league as the clinical anguish experienced by chronic sufferers, so my story shouldn’t be taken as some universal truth.

One thing I can say is, paradoxically, I’m glad this happened to me. It wasn’t pleasant, but I came out the other side knowing more about myself, better able to admit my human frailties and more forgiving of the guy in the mirror. It’s a lesson I don’t need to repeat.