A recent study by Public Health England suggested that 41% of Britons aged 40-60 fail to exercise so much as 10 consecutive minutes brisk walk each month. This is shocking, so much so that I have difficulty believing it, but even assuming it is an exaggeration it does highlight an underlying truth that a significant proportion of middle-aged Britons fail to do any significant exercise.
The focus in the media is on the benefits to your heart. By walking just 10 continuous minutes at a brisk pace every day, an individual can reduce their risk of early death by 15%. They can also prevent or delay the onset of disability and further reduce their risk of serious health conditions, such as type 2 diabetes, heart disease, dementia and some cancers.
The human body is not designed to be sedentary, it relies on movement for far too much. Obviously it survive without movement, people do, but it can't function properly.
There are so many systems which rely on movement some more obvious than others, here's a few, by no means the full list
Joint health - The joints are lubricated by synovial fluid, this nourishes the cartilage which lines the joints, the synovial fluid is spread across the joint surface by a combination of one surface of the joint wiping the fluid across another and by the loading and unloading of joint surfaces causing alternate high and low pressure and pumping the fluid around the joint, both of these processes need movement (weight bearing for the latter).
Bone health - Bone density responds to loading both direct loading from weight-bearing and from the pull exerted by muscles. Activity, preferably weight-bearing, is therefore important to maintain bone-density,
Circulatory health - The heart is not the only circulatory pump in the body, in fact it is not really up to the job on it's own, it relies on other smaller pumps most of which are muscular and rely on activation of muscles through movement to aid venous return. If circulatory pumping is inadequate then there is the potential for stasis, this is how sitting still on a long flight can contribute to the development of a deep vein thrombosis as blood can start to clot when it isn't flowing. Stasis can also contribute to ulcer formation and even in extreme cases the thickening and weakening of the heart's muscular walls.
Antibody response - Studies have demonstrated that the immune system also uses muscular pumping systems to speed up your antibody response to infection. Infective particles are presented and recognised quicker and antibodies are created and distributed more rapidly decreasing the time it takes to counter threats and giving them less time to multiply and increase their potential to threaten you.
Enough time sat here writing this...I'm off for a swim, maybe you should do the same!