I know what you mean about having good days and bad days. I get my share of both but mostly I seem to focus on the bad days, I guess because they are days when i am alone and don't have much to do. Don't feel guilty about not getting things done. They eventually will get done when you have the incentive and want to do them. Don't forget guilt isn't going to get the dishes done so why should you feel guilty. I think we are all in that place where we just can't get some things done. It will all eventually work out. Do you have something you can do such as read or take a walk or watch a movie? It will take your mind off. You do need to give yourself a break.
I remember I answered another one of your posts. You had said you feel most comfortable with people in their 80s. I am 65 so I hope I am somone you can feel comfortable wirh. Things will look up, just be patient and try to take good care ouf yourself.