"To the outside world, they may seem trivial and [if they bother you] people might think you have got anger issues, but it's actually just the accumulation of all these micro-stressors finally taking their toll," says Dr Boardman.
It's precisely because these small annoyances seem petty or insignificant to others that you won't receive the kind of support you might get for bigger issues like, say, serious illness or bereavement, she adds. "Nobody's going to send you flowers because you could find a parking space, are they? Nobody drops off a casserole because they heard you had a rough commute," she adds.
Equally, while we're good at seeking support or advice when enduring a major stress, with a micro-stress we soldier on and don't mention it. But ultimately, that can make it feel bigger.
Few would disagree that modern lifestyles offer more opportunities for micro-stress. Work can now get hold of you any time they like, wherever you are. Technology, for all its benefits, can both frustrate and irritate while time, that most precious of commodities, is in increasingly short supply. It's created a growing dichotomy of living lives that are busier than ever yet often fraught and unfulfilling.
Even before Covid, "many people had begun to feel like bystanders in their own lives," Dr Boardman writes, "fulfilling others' demands and suppressing their own desires while meaningful moments passed unnoticed, beauty went unseen, and connections were dropped." Modern life, she says, has become "a thankless game of Whac-A-Mole".
But the pandemic has created an abundance of new daily annoyances to contend with, from navigating the exasperating complexities of booking a foreign holiday to ordering your drinks in the pub via an app.
In her book, Dr Boardman explores strategies for building resilience, to stop a micro-stress becoming the final straw. For a start, she says it's better to acknowledge these moments and consider why something has bothered us, however small, rather than soldier on.
"All stress is potential stress – it's really our own interpretation of it. How up to the task are we? Are we well rested? Are we eating well? Do we feel good about our personal life? All these questions help to determine just how we interpret any potential stressor that arises. In that respect, everybody tackles it differently because everybody's situation is different."
All these factors drive our behaviour when under pressure. "I'm always amazed by our capacity to do the exact opposite of the thing that would make us feel better in those moments. Often when we're stressed, we just double down. We work through our lunch instead of taking that break we need or you cancel your plans that evening or don't go for a walk. We just don't do what we know we should."
Similarly, failing to deal with micro-stress can also lead to bad decision-making - turning to alcohol or cigarettes or junk food, or hiding away, reducing exercise and social connections.
David Almeida, professor of human development and family studies at Pennsylvania State University, who researches the effects of stress, says people can be divided into two categories when it comes to their responses: 'Velcros', who allow stress to stick to them, leaving them irritable, grumpy and frustrated, and 'Teflons', who can realise just what is happening and just let it slide away.
In a ten-year study, Professor Almeida found that people who are easily upset in the moment and who continue to dwell on their negative feelings are more likely to suffer from subsequent health problems such as pain, arthritis, cardiovascular complications, and mental health issues. The good news, however, is that a Velcro person can retrain their brain to become more Teflon. "People can and do change in their reactivity to daily stress," he says. "One advantage of ageing is that people become less reactive to daily stressors. Perhaps that's due to greater experience of dealing with life's slings and arrows or maybe it's just the different types of stressors we have to deal with as we age."
He reminds us that a little stress in your life is a good thing, and can improve your cognitive function if it creates an opportunity to solve a problem.
"It is impossible to rid ourselves of most of the irritations and anxieties that pop up in daily life," agrees Dr Boardman. "What is possible is to stay fortified in the face of them."