It is hard to explain what it is like living with illness, especially when you often look so normal (well many friends may disagree on this one ;) ) This lady who has lupus has produced what is called 'The Spoon Theory' which conveys as well as anything can a little of what it can be like. For me, some days I start with very few 'spoons' and others have quite a lot, but there is always a limit, and once they're gone that's me done that day (you'll really have to read the link for any of this to make any sense!)
Days where my spoons are few (!) taking Adventure Girl and Boy to school may use them up entirely, and sometimes there are not even enough for that, and Adventure Bloke steps in and takes over, as he always does so gracefully. Has done today, in fact, as I assessed this morning that my spoon number may be somewhat low today.
I hope that goes some way towards explaining what it can be like?