The wristband and the photograph which showed me that it is time to make some changes

Participants are strapped into a row of seats which is then winched high in the air before being released to sway back and forth above the tips of the trees.

Before we were allowed to board, we had to be checked in and weighed so that the apparatus could be safely set to deal with our combined mass.

The woman at the reception desk gave us each a wristband and then wrote our weight on it, to be shown to the staff at the swing. I looked at the number she had scrawled on the bit of paper wrapped around my arm.

I shuddered and then thrust my hand deep into my pocket.

Minutes later we were securely harnessed in the swing and the process of winching it into the air had begun. My son, previously bullish about the ride, found that his confidence had suddenly failed.

"I want off...I’m serious daddy…let me off!”

I also began to doubt the wisdom of what we were doing. As the swing inched higher backwards, my not inconsiderable weight began to transfer forwards, leaving the impression that I was about to topple out of the seat and fall into the valley deep below.

I quickly looked at the figure written on my wrist and found that my earlier view had reversed. Now I was hoping desperately that their scales were accurate.

When we reached the top, a staff member on the ground gave us a thumbs up. Amid the howls of protest, I decided that further delay was unwise and firmly yanked the rope which released the swing mechanism.

There were screams of terror, which were quickly replaced by delighted laughter as we swung back and forwards several times.

Later, back in the car, there was excited chatter about what we had experienced.

My son, proud of overcoming his fear, insisted on reciting the experience over and over.

“What was the scariest bit?" he began. “For me it was when we were high in the air, waiting for it to start. What was the scariest bit for you daddy?”

“Yeah, the same.”

Although, I knew that, for once, I was not telling the truth to my son. Without doubt, by far the scariest moment for me was when I saw what my current weight is. I do not have scales in my house, and I don’t routinely track how much I weigh.

Despite this, I suppose I have been aware for several months that my girth has been increasing. My son likes to joke about ‘Daddy’s big fat belly’ and I’ve always laughed along, hiding the tinge of regret that I always experience.

There are a few reasons for my expanding waistline. I’ve always tried to live an active lifestyle and take regular exercise, but recently I’ve been failing at that. Last year, I left the tennis club which I had been a member of for a long time.

Work commitments meant that I simply could not afford to justify the fees when the time I was able to give to the leisure pursuit had become vanishingly small.

I told myself at the time that I would continue to play, I would organise matches with friends on a more informal basis. But without the routine of being in the club, it just hasn’t happened.

Then there is my running. Over the years I’ve helped to keep myself fit by participating in timed runs. I set myself the goal of completing 100 Parkruns as a motivation. About a year ago I achieved the century.

The next milestone of 250 runs seemed a world away and I’ve found it increasingly difficult to haul myself out of bed to participate.

Twelve months on and I’m still anchored on 100 Parkruns completed.

The bigger problem is my diet. Simply put, I am a binge eater with an almost insatiable addiction to sugar. While I was disturbed to learn my weight, considering the amount of rubbish I consume on a weekly basis, it is actually close to miraculous I am not twice the size.

Portion size is the main issue. I will easily consume twice or three times the sensible amount of food and still want more.

The part of my brain which tells me enough is enough seems to be on permanent vacation. At almost every meal I will keep going until I feel sick afterwards.

And between meals I am usually grazing on chocolate, crisps and sweets which I bought on the false pretext that they are for my son.

During our recent holiday there was a second moment which caused me to undertake some deep self-reflection. Following a visit to an amusement arcade my wife sent a photograph she had taken of me with my son.

We are on a fairground ride which is about to begin. We are gazing at each other, lost in the moment, oblivious to the outside world. To me, it is a pure representation of unconditional love.

I want to make sure that there are many, many more photographs like that and that is the best motivation to start making better choices.

I do not want to do anything too dramatic. I don’t foresee myself running too many marathons in the future and a gluten-free vegan diet composed entirely of grains, seeds and pulses is probably not the most realistic prospect.

Vanity is not chief among my vices, but I also don’t want to feel embarrassed by how I look. I want to feel healthier for the benefit of family, but also for myself. I know from previous experience how closely aligned good physical and mental health are.

Which means hauling myself out of bed to become a bit more active, eating more sensible portion sizes and limiting the grazing between meals. It’s time to make some changes.