Lack of stamina

Lack of stamina is an inability to maintain or sustain prolonged stressful effort or activity. However, with a patient suffering from ME, the ability to maintain or sustain even minor effort or activity, be it physical or mental, isn't possible. This lack of stamina is more easily quantified in severe and very severe ME.

The CDC only officially recognizes ME/CFS, so ME patients are sometimes categorized as "severely affected ME/CFS patients" by them. However, ME/CFS patients can also be severely affected.