How mild can CFS be and still likely be CFS? The symptoms completely match, But I've never once been too fatigued to go to go shopping or walk through an airport. My chief complaint is from going from top athletic shape to feeling fatigued an unable to exercise. And I've been tested for anything and everything that any doctor I've seen could think of that could be causing it. so we've basically done the rule-out for everything else. so in some sense, if it really is CFS, I'm currently lucky. And when CFS is mild (particularly compared to people that can't get out of bed), does the likely viral causes change? I was in excellent athletic shape before the onset. my chief complaint is fatigue during and after exercise. I initially described it as feeling like I hit my lactic threshold within a few minutes at what use to be easy speeds for me. I also described it like feeling like I did a workout yesterday even when I had rested for a week. And I would feel physically sore after even short aerobic exercise. I have terrible insomnia. my insomnia predates the fatigue by a few years, but since the fatigue onset, it is really really bad. I use to function normally with ambien managing my fatigue. It just isn't sufficient anymore. I still feel exhausted when I wake up in the morning. The first symptom at onset was an episode of arrhythmia triggered by excercise I get brief moment of light-headed-ness almost every single time I go from sitting to standing or reach from standing the ground to pick something up and stand up. There is a delay of about 5-10 seconds and then it hits for 5-10 seconds and then goes away. It is like a delayed poor appetite, and I gained a little bit of weight anyway. which could be attributed to almost no exercise. raynaud's which shows up even at temperatures as warm as 64F.