Some people equate stress to the slow slide to chronic inflammation.
Too many stimulants and depressants will cause the body to deregulate itself.
Too many viral and bacterial infections will cause cold and flu symptoms.
An ongoing sleep deprivation will add to obesity and other problems like diabetes.
All stress that taxes the immune system is harmful.
It means eat well, exercise well, sleep well and live well. There are no short cuts to well being.
If you want to understand the idea of stress. Think about biological stress.
https://en.wikipedia.org/wiki/Stress_(biology)?wprov=sfti1