By Marc Nohr, Chairman

We have incredible talent in the world of advertising. But we don’t always take care of it – and that includes ourselves.

One of the main reasons for this is that we work in a high-pressure service industry, with a long-hours culture. When I founded my first agency, Kitcatt Nohr, I was sometimes at my desk for 7am, not leaving till midnight, several days in a row. Long hours are worn like a badge of honour; we’ve all been there.

But what is sometimes necessary, in extremis, has become commonplace and even routine, and always-on tech has only made it worse. This has to change – not just because it’s unsustainable in terms of mental and physical health, but because it’s also inimical to creativity.

As a leader, your power to make things happen relies a lot on your state. That is determined by a range of factors, such as your mental health, physical health and how stimulated you are.

Two years ago, I moved to a four-day-week contract. Am I healthier, happier and more fulfilled? Broadly, yes. But I have also become far more productive and experienced some real career highlights in that time.

This week, I was honoured to be included in the Timewise Power 50, which celebrates senior executives working flexibly. Of all the leagues and lists in our business, this one deserves more attention. If we are to thrive rather than survive, we need to learn to treat our people and ourselves better. By publicly talking about my decision and how I make it work, I hope I can encourage more leaders to embrace flexible working themselves and welcome it at all levels of their organisations.

Why did I decide to work part-time?

I needed a bit of headspace, and more varied and diverse days. We all know there’s a law of diminishing returns when it comes to working longer hours – and certainly when it comes to sitting in meetings or at your desk, which as my former business partner Paul Kitcatt once said to me is “a very dangerous place from which to view the world”.

I determined a few things that were key to me and realised I had the luxury of choice. By moving to a four-day-a-week contract, I could do more of those things.

What were the biggest barriers and challenges?

The biggest barriers are how you organise your time, thinking through what it means for your team and communicating really clearly. When one of those things is missing, that’s when it goes wrong. It can’t be a one-way street; it requires buy-in from everyone. You have to set your boundaries and people need to respect them, but you also have to be good at maintaining them. That includes limiting the access technology affords. Sometimes it’s about switching off; sometimes it’s about switching lanes and doing other things. It’s also about having a fantastic team whom you trust – which I’m lucky to have.

The biggest challenge, by far, was not feeling guilty or compelled to treat my fifth day like any other. I had to change my pattern and routine, then recommit to it every day, every week. The creep happens. Remind yourself of what’s important rather than urgent, which applies equally to what you chose to do and what you chose not to do. Time, just like energy, is finite and you have to prioritise.

This is not just a niche issue for returning parents. It applies to everyone, including someone on a full-time contract. We all need to be alive to what makes us most effective and what promotes our physical and mental health.

What have been the highlights?

The ability to think, learn, discuss and reflect outside the confines of an office and our industry is hugely rewarding. Getting a more varied diet of stimuli makes me more productive, more creative, more interesting and interested. I feel fitter, more balanced and more inspired: 100% committed, 80% contracted.

In terms of tangible achievements: selling a majority stake in Fold7 to Miroma Group and taking on the role of group chief executive of its agencies (while promoting from within to facilitate that); working to develop a new commercial model for the industry by chairing the IPA Commercial Group; helping to create a five-year strategic plan with JW3, as well as mentoring the next generation of entrepreneurs – these are things I’m proud of and could never have made happen without flexibility.

How has a four-day week changed how I work?

I looked to some of the most amazing people I know who operate at high levels and who observe their own schedule and I realised there was a connection. One of my oldest friends is very senior in the music industry, flies all over the world but is in the office just one hour a day. Another works from home every morning and sees people in the afternoon. They are some of the most productive people I know. Creativity doesn’t happen between nine to five.

I also thought about the words of former US senator Joe Lieberman in The Gift of Rest and how observing the Jewish Sabbath is a cornerstone of his week. Switching off for at least a day is vital. Religious Jews have been doing this for thousands of years for a reason. They have ritualised rest and protected it within the week.

We all need to start being more thoughtful about the modern working environment. We thought tech would liberate us, but all it did was extend our working days. The power of tech means the whole world is at your fingertips. These devices in our pockets are amazing, powerful tools – but left to their own devices (no pun intended) they are hugely preoccupying and drain our productivity.

You can make positive decisions about simple things to combat this. You decide when to turn your phone on; you decide when to shut your laptop. Ask yourself: will the world implode if I don’t answer that email until tomorrow?

Things do turn up on my Friday – of course they do. But I’ve found people are respectful of my time. If I get asked to a meeting on a Friday, I say: “I’m sorry, I don’t work that day, but if you really need me, you can call me. And we’ll meet another day.”

Is it easy to work part-time in a leadership position? In a word – no. Like with any big decision, you need confidence to make a change. You must remake and reinforce that decision every single day. You must ritualise change yourself. This is how we learn to do new things.

Working part-time has reinforced the benefits of being in an office for collaboration and group working, and the benefits of solitude for deep work, reflection and original thought. I’ve also learned that my dog is on better terms with Ricky Gervais than I am, every time we bump into him on a Friday.

What do I wish others knew about working part-time?

We can’t multitask; it’s a myth. All it means is your attention is shallow and split between competing demands, as opposed to focused or “deep work”, which is meaningful and substantive.

The most fundamental shift required is moving from thinking and talking about “input” – how many hours you put in – to thinking and talking about “output”, which is how effective you are.

Working flexibly allows time and space for proper, deep, considered work. To do deep work, you have to switch off sometimes. I’m evangelical about it. This stuff goes so deep behaviourally. When you are overloaded, you are just processing (if that). If you are running from meeting to meeting with no time to even look over your notes – you’re surviving, not thriving.

My advice to anyone thinking about working flexibly is that you need confidence to make a change and make it work. As someone once said: if you think you can, you can, and if you think you can’t, you’re probably right. So be brave, plan it well and make it happen. Is it worth it? A million times yes.

How to make flexible working work for a creative workforce

Be a student of your own productivity
Understanding your body and mind is a constant project. Think about what rituals, routines and tools will help you get there. These support systems are critical to making it work. And be brave enough to ask for it.

Change your mindset from input (hours) to output (how effective you/your team are)
Establish what you need and what you will deliver. Be brave, plan it well and make it happen.

Communicate really clearly to your boss, team and clients
When you change your routine, set your boundaries, reinforce and recommit to them daily. This is the only way it works.

Flexible working is not a female or parenting issue; it’s a people issue
There are many ways to be effective. For some, it’s starting early or late; for others, it’s working away from the office or working fewer days. Everyone – all levels and genders – benefit from working more flexibly, including those on full-time contracts.

Treat people like grown-ups
Culture is as important as any formal working arrangement. Trust people to work in the way that best works for them and they will reward you with their best work. It engenders loyalty and attracts the best talent.

Limit your use of technology, especially on your day ‘off’
The ability to focus when working and rest when you’re not is fundamental to your productivity as well as physical and mental health.

Read more from Marc here

You can also watch Marc talking about this topic on BBC News here