Logging on to my laptop, I emailed my secretary telling her I needed to work from home for a few days after coming down with another bout of flu.
The first bit was certainly true: I could barely get out of bed, never mind leave the house. But what had floored me wasn't a bug, but another episode of the depression that had dogged my life for as long as I can remember.
Depression that left me paralysed, tearful and unable to cope with the simplest task. Depression that I lied about to myself and concealed from nearly everyone else - certain that revealing the truth would stop my successful career in its tracks.
No wonder. Perceived stigma surrounding mental health problems persists: this week, Ruby Wax, who has courageously spoken about her depression, advised against transparency with employers.
"When people say 'Should you tell them at work?' I say 'Are you crazy?' You have to lie," she said. "If you have someone who is physically ill, they can't fire you. They can't fire you for mental health problems but they'll [find] another reason."
It's no coincidence that people use language like "coming out" when confessing to mental health issues. There is the fear that your true self will not be accepted, or that it could be held against you. It has taken me years to realise the opposite is true: in my case, being open about my struggles with depression with peers and seniors has liberated me.
My previous coping strategy was to lie and withdraw. I was a bloody good actor - my career was flourishing and colleagues would have described me as happy and successful.
Having started out at PricewaterhouseCoopers after graduation, I later joined KPMG as a manager, ascending the ladder to become a director within their financial advisory practice. Along the way I married and had two beautiful daughters, now aged seven and five.
On paper, I was a success. In reality, I was wired, glued to my BlackBerry and endlessly fielding deadlines. My alarm would go off at 4.30am and I'd be in the office by 7am, putting in a 10-hour day, then clocking up another three hours' work after putting the kids to bed. Surplus energy was spent surviving the dark weeks that came with increasing frequency.
I lost count of the times I managed to keep it together until I walked through the front door, where I broke down in tears. Other days, I would feel unable to get out of bed: never mind getting through the day, I couldn't even start it.
Things came to a head around five years ago, when my wife, who had long borne the brunt of my condition - the tears, the anxiety, my inability to cope with the minutiae of family life - was able to persuade me I wasn't just stressed, but depressed, and needed to see a doctor.
In some ways, a diagnosis was a weight off my shoulders - my GP put me on anti-depressants and I thought "job done".
Of course, it doesn't work like that. The drugs helped, but three or four times a year I was still felled by another episode of "flu". It didn't even occur to me to tell colleagues the truth: how could anyone admit to this kind of illness and continue to build the career I wanted?
Crunch point came with an invitation to a talk arranged by three major firms who had formed the City Mental Health Alliance. I went purely as an observer, but found myself surrounded by fellow executives talking openly about their mental health.
When someone asked why I was there, I found myself answering: "Because I suffer from depression." It was a cathartic, lightbulb moment - the first time I ever said that word out loud among my peers. The sky didn't fall.
I was encouraged to raise my head further above the parapet when KPMG's chairman, Simon Collins, gave a speech in which he called on staff to bring their "whole selves to work", which felt like permission from the top to be myself. I was going through promotion at the time and his statement meant I felt able to confide in my sponsors both my fears and my illness. They couldn't have been more supportive.
When I shared my experiences in the company magazine, the reaction was humbling and overwhelming - hundreds of emails thanking me for speaking out, telling me they or someone close to them had the same struggles.
We've made tremendous progress in the past few years but we are still a long way from people feeling confident about being very open. A culture of silence allows long-held stereotypes to flourish. We need to create the opposite.