Fatigue and the Anxiety/Depression seesaw

The hardest symptom for my family to comprehend is the overwhelming fatigue that I feel.
Sometimes it is mental fatigue from all of the confrentatiions of those thoughts that create my anxiety while other times it is physical fatigue from the decreased stamina that sneaks up on you before you know it.
I used to run at least 3 times a week and now it is all I can do just to get myself outside to walk. The depression strengthens as the anxiety of what I should be doing is amplified by family members "suggestions" that I should be doing certian things.
I know I am not my anxiety but it seems like I have to keep reminding people about it when I do not meet their expectations that lie outside my mental and physical abilities that constantly change.