I feel myself devoid of energy when I come home from the office but when I go for a walk or play badminton etc with friends, my body re-energizes. I think our modern day lifestyle, which have become very lethargic and devoid of physical activities, is also the reason of the fatigue besides of the reason you mentioned in your post.
Definitely, these diseases and abnormalities are the reason of the unusual fatigue our body and mind are feeling in modern time but these conditions are also becoming worse due to our lifestyle in which physical activities have become less important for us.
Your post is full of valuable life saving information. Kudos to you.