Stress - if I rememeber my studies from years ago - was a concept developed by Hans Selye who defined it as anything that required adaptation on the part of the organism stressed. So, getting married or being promoted at work would certainly be stressful! It feels to me that there must be some difference between positive and negative stress but I seem to remember that it is the degree and number of changes over time that add up to the total amount of stress. This is at a cellular level, I think, and perhaps has to do with the extent of the changes requires to adjust to the new situation and to respond to it adaptively.

Somehow, exercise - and I'm guessing meditation, social support, prayer, etc. seem to mitigate that stress reponse. Remember that scale where - if you scored 300 points or something in a year, you had a high probablity of developing an illness? That's it.

I do agree that this kind of works aS a general model of illness. Probably even helps account for who succombs to infection and who doesn't - as least statistically, probably not going to explain it on an individual basis. Then we have genetics, just to add a touch of complexity....