We spend, on average, almost nine hours a day sat down - and that's not taking into account the eight hours we spend lying down, asleep.
You might be sat there thinking 'not me', but when you break your day down into time spent commuting, sitting at work, commuting back home again and sitting down to binge-watch Netflix of an evening, it's easy to see how we manage it.
But our bodies aren't designed for such lazy living, they're designed to move.
"We can see this from the way our bodies are structured," Mohamed Taha, clinical director at Form Clinic, told HuffPost UK.
"We are made up of 360 joints and over 700 muscles that move your skeleton. Our vascular and nervous system depend on movement to function."
To highlight the effects of a sedentary lifestyle on the human body, we spoke to experts about how sitting down all day impacts various organs and bodily systems.
Back And Shoulders
Many of us have felt the effects of sitting for long periods, especially on our back and shoulders. But why?
Taha explained: "The average person is not able to sit down for more than three minutes without falling into a slumped or 'slouched' posture.
"Over time, this creates wear and tear in your discs and joints, overworks your spinal ligaments and puts an enormous strain on your back muscles that are stretched to accommodate this slouched posture."
Additionally, if you are in front of a computer, it's natural to hold your neck forward while concentrating, which can cause strain on the neck and shoulders.
Legs And Hips
According to Dr Clare Morrison, GP at online pharmacy MedExpress, sitting down for long periods can "lead to muscle atrophy in the leg and gluteal areas, where the muscles weaken and waste away".
"Sitting also causes hip flexor muscles to shorten, leading to issues with hip joints," she adds.
Another issue is that prolonged sitting can lead to poor circulation, added Steve Iley, medical director of Bupa UK. This could lead to swollen ankles, varicose veins and even deep vein thrombosis (DVT).
Heart And Cardiovascular System
Humans are built to stand up – and our heart and cardiovascular system work more effectively this way.
"Too many of us are tied to our desks, and research shows that this could be increasing our risk of developing heart disease," said Chris Allen, senior cardiac nurse at the British Heart Foundation (BHF).
A 2010 study compared adults who spent less than two hours a day in front of a TV versus a group that spent more than four hours a day in front of one.
It discovered an increase of about 125% in cardiovascular disease in the group that spent more time sitting down, as well as a 46% increased risk of death from other causes.
Additionally, research from the University of Chester in 2013 found that sitting down burns 21% fewer calories per minute than standing up - a solid case for investing in a stand-up desk.
"Long periods of sitting are also responsible for deactivating an enzyme called lipoprotein lipase," added Taha, "which is responsible for the breakdown of fats in the blood vessels, and can lead to blockage of the blood vessels of your heart."
When you sit down all day, you also reduce the amount of oxygen entering your body.
"Lung compression from this posture, which results in less space for your lungs to expand when you breathe, limits the amount of oxygen that fills your lungs," explained Taha.
"Sitting down can limit the fresh blood and oxygen going to the brain, meaning it can decrease levels of our 'feel-good' hormones, endorphins, and slow your brain function," explained Iley.
"It has an impact on your mental wellbeing, not just your physical health."
Taha added that we might also find it difficult to concentrate on certain tasks as the day progresses. This is because "the longer we sit, the more sluggish our brain becomes".
This, he said, is partly due to the limited amount of oxygen absorbed by your lungs.
Diabetes is also a well-known factor linked to prolonged periods of sitting. In 2011, a study showed a decline in insulin response within just one day of prolonged sitting.
"Muscles that become inactive don't respond as easily to insulin - a hormone that is produced by your pancreas that helps with the breakdown of glucose for energy," explained Taha.
"This means that the pancreas is having to produce more and more insulin to break down glucose, and this often leads to diabetes."
Sitting down can cause your abdomen to compress, which slows down digestion. This can lead to issues such as bloating, heartburn and constipation.
Additionally when we're sat down, our bowel functions less efficiently than when we're stood up, Dr Morrison explained.
"In fact it's common for people who are in hospital to suffer with bowel problems, because they are sedentary."
Sitting down can have a "severe negative impact on overall health and wellbeing", warned Steve Iley.
But it is possible to build a healthier routine into your lifestyle, to counteract a sedentary job.
"While more research is needed to fully understand the link between sedentary behaviour and heart disease, it's well established that at least 150 minutes of physical activity a week helps to lower the risk of a heart attack or stroke," said Chris Allen from BHF.
"We would urge everyone to get up and get moving at work – whether it's taking a brisk walk at lunch or dusting off that old bike for the morning commute."
Mohamed Taha recommends other simple ways to get moving throughout the day, while in the office. These include:
:: Stand up when talking on the phone.
:: Set a timer on your phone for 30 minutes and standup from your desk and walk around for a minute or two.
:: Have standing or walking meetings.
:: Learn to improve your seating posture. "The better you sit, the less the effects on your spine, ribcage and lungs," he explained.
:: Invest in a standing desk or a specialised treadmill-ready vertical desk.