Most illnesses start in adolescence and young adulthood. By age 40, they either progress or lead to other problems, or both.
The causes of illnesses at an early age are extremely clear, and I have already written about them, these are only three factors - genes, infections, toxins . This triad should be remembered by everyone. There is nothing else given here. Yes, someone will now think about injuries, but this factor is more an exception than a rule.
For example, in youth, many people develop AIT, which is often preceded by either parents’ genes or tonsillitis and other throat infections, or all of these together.
Another example is the accumulation of bilirubin. Genes. In Gilbert's syndrome or similar ones, a person is poisoned from youth by the product of the breakdown of red blood cells - indirect bilirubin. Its accumulation in tissues leads to constant activation of the immune system, and as a result to chronic inflammation.
And even when we consider a person with good genes, he also becomes vulnerable at a certain age, due to the accumulation of the consequences of infection and toxins.
For example, let's take a hypothetical "alpha man" (this could also be an "alpha woman 
"). In their youth and early adulthood, such individuals are super active, this includes sports, girls, alcohol, and risky activities. All of this leaves an imprint on the body. Sports are oxidative stress, bad sexual partners are infections (for example, venereal diseases), alcohol/drugs are toxins, risky activities are stress and toxins, etc. That is, as a result, such a person by the age of 40 will also have problems, even with his genetic potential, which he can stupidly squander.
Why am I writing this? :) Because when different people contact me, they should understand that correcting their health is not only taking supplements. If you spent half your life "hanging" on all sorts of horse parties, loved to drink, smoke, sit at home for a long time after all this, taking antidepressants, THEN the concept of karma is appropriate here as nowhere else.. And it will be difficult to help you, with all my great desire!
Similarly, if you are unlucky with your genes, then your path to health should begin with developing your intellect and earning big money. Because in order to compensate for your genes, you need genetic tests and supplements and expensive healthy food and housing in an ecologically clean place and much more.
In general, I'm trying to say that you need to understand and take care of your health from a young age. Understanding that we are all essentially biological machines, the breakdowns of which are difficult to repair, and sometimes simply impossible.
