I don't have ME. But I have several illnesses that strongly cause fatigue. I know it's not the same, especially in that I am not sensitive to light and sound. But I have absolutely no energy. I can walk farther now, I used only walk five minutes, can do 15 now. It means the world since my stores are 10 minutes away.
I mostly have bad days. I try to live for the good days. But I often can use the computer so I have that which is very lucky.
I can relate to bad lung capacity, one of my issues are compression fractures of the spine, I have three, and in general one cause 10 % of decreased lung function so i should work at 70 %, but it really feels less. That part is really hard.
I have many people telling me how active I should strive to be. Most of them tell me I should totally ignore what I feel. It's basically what made me this ill.