I came across Spoon Theory today:
The basic idea is that [the chronically ill] have a limited number of spoons available for the day and each action will cost a given number of them – the more demanding the task, the more spoons would be required. The phrase "running low on spoons" can be a useful way of communicating the need for rest
I see this sometime with Emma: her various illnesses and sensitivities catch up with her and she has little capacity to get things done for a few days. At other times, such as today, she has quite a reasonable amount of energy or “spoons”.
I enjoy good health, as confirmed at my annual physical today, and I have a large number of spoons that I can draw upon.