I recently attempted to explain PEM to a group of people. I don't know if I did a very good job, but it was the best I could manage. I explained that the PEM in CFS is was forces patients to be "lazy", that is, to self-limit their activites in order to keep within their envelope of energy. If we overdo it, PEM is what follows. We look just fine during the activity, but when we overdo it the price is paid afterwards. I didn't think of this then but I should have said that it's like going into debt...you can purchase things just as easily as if you had cash, but you know you'll pay for it later. I described PEM as "fatigue so intensely profound that it is very extreme suffering, even at rest. It is not simply "miserable", it is beyond imagination and you're just screaming internally because the level of suffering is unfathomably high, and yet you're so weak that it's all you can do to take the next breath." I explained that when they first get ill, CFS sufferers usually have many attempts of trying to force their way through this, and they keep trying often for years until they are personally convinced that it cannot be overcome by sheer willpower. They learn, instead, to buget their energy, which in modern terms equates to "lazy", in order to have any semblence of living, and only give themselves the luxury of exerting themselves beyond that on special occasions. I made sure to mention that despite being forced to be "lazy" we're chomping at the bit to do something, ANYTHING, and gladly enjoy sometimes even mundane chores as our special treat that's worth the PEM backlash. The group appeared to take it very well. I know that most of us here consider PEM to be the hallmark CFS symptom. How would you describe it in your own words? How do you help people to understand?