My worst time, normally, is just after breakfast when I am "done in" and have to rest. After a short rest I am OK. I much regret being as I am, but it has left me with a great deal of sympathy for those with conditions like ME and MS. Before, I had no idea what total exhaustion meant.
Today, I put some plants in the garden. In the past this would have been trivial, but I was totally exhausted and had to rest to recover. It is very hard for others to understand.