I do not think that it is unusual to have a lack of motivation or enthusiasm. Particularly in the society we live within today. Occasionally we all get a bit bored or tired of the same routine day in and day out. I myself and friends that I have spoke with-feel like this from time to time as well. If you have been feeling like this more than three times a month, possibly you are starting to suffer from some sort of depression, or could have undiagnosed mixed bipolar disorder. Or on the other hand, maybe your going through a change of life. I know some women experience this when they reach a certain age. Also schedule an appt. with your physician. Maybe your overdue for a good physical exam, that could uncover a slight deficiency in iron for example. Also eating too much sugar, could also give you the blues. Hope some of my advice and suggestions helps you out somewhat. Remember though-you are not alone, because a lot of people out there have experienced this during one time or another throughout their lifetimes.