The human body has evolved over the course of the ions to become a workhorse and it does not understand to stand still. If it is not exercised regularly, if it is abused occasionally and if it is treated perfectly, it will fail somewhere and gradually. I am not a messenger, these are the facts that I observe

Weight gain

Lack of energy

Weakened social life

Accelerated aging

Risk of depression, anxiety

Increased procrastination

Stagnate at all levels.

.Physics: muscles atrophy

Brain: watching TV and doing nothing for others, we end up learning nothing and even no longer thinking.

Social: Generally, social activities help to exercise the brain and strengthen memory.  

Well, the biggest risk is not to move and therefore not to evolve.

When nothing happens to us, we don't move, we become lazy, see assisted and we evolve more.

Not evolving, it comes down to stagnating and therefore to more or less death (without exaggerating).

It is important to have a minimum of mental comfort, to feel secure, but it is important to never settle into mental comfort, otherwise you will no longer evolve.

There is a wide range of adverse effects that a human may experience as a result of living a sedentary life. Some of them include cardiovascular disease mortality, all-cause mortality, risks of metabolic disorders like hypertension, dyslipidemia, and diabetes mellitus, and risk of developing cancer. That's why increasing physical activity is important to reduce sedentary behaviour and promote public health. 

You may experience the following problems if you have an inactive lifestyle:

• You gain weight due to burning a few calories

• You may lose muscle endurance and strength because you are not using them as much

• You may get weaker bones and lose mineral content

• Your immune system may not be able to work

• You may end up developing a hormonal imbalance

• You can suffer from poor blood circulation

• You may suffer from more inflammation 

Sedentary lifestyles can have a number of negative effects on your health. Prolonged sitting can lead to increased risks of obesity, diabetes, heart disease, and certain types of cancer. It can also cause poor posture, muscle imbalances, and decreased flexibility. Additionally, those who lead a sedentary lifestyle may experience lower energy levels, increased stress, and a decreased ability to focus.