"I was working non-stop. The company was almost like a love affair. I call it 'my greatest love affair', because it felt so, so important.
"My identity was so wrapped up with work. If I wasn't doing that job, I didn't really know who I was."
In 2017, Amber Coster was a glamorous highflyer in a senior role at a successful tech start-up, in her late 20s and travelling the world.
"On paper, my life looked incredible," she says.
But she was ignoring some significant signs that all was not well.
"I used to say I was sick and tired of feeling sick and tired," Amber says.
And in addition to chronic fatigue and nausea, she was having migraines, extreme abdominal pain, skin rashes and eczema. Her GP diagnosed a recurrence of teenage glandular fever. And Amber, who lives in London, took two weeks off work to recover.
But things got worse.
"I lost my words - I couldn't speak properly," she says. "I'd sit at dinner with my partner and ask him to 'pass the post' instead of 'the water'. I couldn't read numbers. I couldn't walk down to the shops - I'd have to sit down on somebody's garden wall."
As the two weeks off turned into six months, doctors carried out countless tests. One told her she had the blood-test results of "a 20-year-old Olympian".
"I just cried," she says. "I knew that there was something wrong and I felt crazy."
What the doctors didn't know - and Amber herself hadn't confronted - was she had been working extremely hard. She had regularly been getting up at 05:30 to send emails, working through until 23:30, when she fell into bed, and cancelling weekend plans in order to do yet more work - all the while telling her team to ensure they made time to relax.
Nobody had said anything to her about her own routine. Even when she had made an effort to spend fewer hours working, she had felt unable to switch off.
She describes the company, where she had been a senior manager, as "a very aggressive, high-sales, revenue-first organisation". Its product was software enabling other businesses to run 24-7 and Amber says she had felt like she was becoming a part of the tech herself.
"We spoke about greatness a lot. And we spoke about 'lion culture'.
"We spoke about being strong and we spoke about being brave and doing things that other people don't do. We spoke about being 'exceptional'."
Eventually, after she turned to a psychiatrist, Amber realised it was her mental health rather than her body that was, in her words, "broken".
Physical symptoms of burnout are a common warning sign, sleep expert and author Dr Nerina Ramlakhan says.
"I've seen a great deal of this - and I'm seeing more and more of it. The way in which we're using technology and information and screens puts us very much 'in our head'.
"If we were paying more attention to what's happening in the body and getting off that mental treadmill, we would notice the niggles, the little aches and pains, the little early warning signals long before they become huge, great crescendos and screams for help."
Dr Ramlakhan advises taking screen breaks, however small, as often as possible - on the commute, in the bathroom, at lunch, keeping phones out of bedrooms at night, alongside healthy eating and going to bed at a reasonable time.
"Little things like that can start to make a difference after seven to 10 days," she says.
Dr Ramlakhan's spiral of burnout
- Step 1: Constant feelings of pressure and anxiety; a feeling of having too much to do; waking up with it in the pit of your stomach, starting the day with coffee and your phone
- Step 2: You stop taking breaks during the day; you start working longer hours, you're taking work home with you; your work spills over into your weekend, your family time; you're even sitting on the toilet working
- Step 3: Physical symptoms will bubble up: this might be headaches and migraines, or irritable bowel, or cold sores or lots of little niggling colds, which just don't go away, or aches and pains in the body
- Step 4: Until now your work is probably unaffected but your behaviour may become more erratic, more impatient, more arguments with colleagues, you are more tetchy, irritable, you may make more mistakes or become irrationally perfectionist; you feel unable to delegate anything; you might start to have very serious muscular-skeletal problems, back problems, neck and shoulder problems
- Step 5: Clients might start to complain; then, you hit rock bottom, serious burnout, serious anxiety, depression, serious medical problems, and that's where you could be signed off
Amber recovered and returned to her job.
She started doing some coaching around mental health and colleagues began to open up to her: the father who felt unable to talk about his children in the office because he feared it was a distraction; the woman whose marriage was failing because she wasn't spending time with her partner; others who felt unwell but worried they simply "weren't tough enough".
But when she discussed making changes at the company at a senior level, she was met with a mixed response. On the one hand, they cared about the staff, she says, but on the other, they believed her experience was uncommon and most people "needed a bit more of a push" to get their jobs done.
Amber has now left her old company, bought a house, got married, run a marathon and started her own company, Balpro - with a mission to "help businesses balance aggressive revenue goals with employee wellbeing".
"I used to believe that 'exceptional' was making sure that PowerPoint [presentation] was perfect, or we were getting that deal, or that this training was above the bar," she says.
"What I now realise is that exceptional is finishing work and having dinner with your kids, or being present for a friend who's in need. Exceptional is standing up and saying, 'Hey, I need some help.'"
Tech may be part of the "always-on" problem but entrepreneur Jana Dowling believes it could also hold the solution.
A serious mental-health crisis inspired her new app, designed to help people track their mental health in the same way they might track their diet, weight or workouts, and look for correlations in data between, for example, anxiety levels and sleep, or caffeine consumption and work stress.
The app, MyArkeo, has received over £1m ($1.2m) in investment.
"We're here to change the way people think about what it means to be fit, to include tracking their mental fitness," she says.
It is aimed primarily at 25- to 40-year-old professionals.
And the questions asked by MyArkeo can be answered only once a day, in order to avoid additional anxiety or encourage excessive screen time.
"We're not a diagnosing tool. We're not a treatment tool," Jana says.
"We're built as a tracking-performance tool to help people enhance their lives and their mental fitness."