Some days are diamonds, some days are stone

Do you ever have those days when you just don't seem to achieve much? I guess it happens to people who are self-employed a little more than people who work in offices etc. so I tend to have them now and then. It's not that I don't have things to do - I am working hard on getting some of my short stories published at the moment and also getting two online shops set up for my greeting cards and my vintage stuff - but some days (like today) just don't seem to have any 'scores on the board' when they come to a close. You feel as though you've just frittered away at the edges of things instead of really getting anywhere. There's always tomorrow, I guess. Do you have days like this?